SUPPLEMENT
Obstructive Sleep Apnea and World Trade Center Exposure Michelle S. Glaser, MPH, Neomi Shah, MD, Mayris P. Webber, DrPH, Rachel Zeig-Owens, MPH, Nadia Jaber, RPA-C, David W. Appel, MD, Charles B. Hall, PhD, Jessica Weakley, MPH, Hillel W. Cohen, DrPH, Lawrence Shulman, DO, Kerry Kelly, MD, and David Prezant, MD
Objectives: To describe the proportion of at-risk World Trade Center (WTC)exposed rescue/recovery workers with polysomnogram-confirmed obstructive sleep apnea (OSA) and examine the relationship between WTC exposure, physician-diagnosed gastroesophageal reflux disease (GERD), and rhinosinusitis and OSA. Methods: A total of 636 male participants completed polysomnography from September 24, 2010, to September 23, 2012. Obstructive sleep apnea was classified as mild, moderate, or severe. Associations were tested using nominal polytomous logistic regression. Results: Eighty-one percent of workers were diagnosed with OSA. Using logistic regression models, severe OSA was associated with WTC exposure on September 11, 2001 (odds ratio, 1.91; 95% confidence interval, 1.15 to 3.17), GERD (odds ratio, 2.75; 95% confidence interval, 1.33 to 5.70), and comorbid GERD/rhinosinusitis (odds ratio, 2.31; 95% confidence interval, 1.22 to 4.40). Conclusions: We found significant associations between severe OSA and WTC exposure, and with diseases prevalent in this population. Accordingly, we recommend clinical evaluation, including polysomnography, for patients with high WTC exposure, other OSA risk factors, and a physician diagnosis of GERD or comorbid GERD and rhinosinusitis.
H
undreds of studies have confirmed the relationship between work at the World Trade Center (WTC) disaster site and subsequent respiratory health issues. Lower respiratory conditions were quickly identified because of obvious symptoms of cough, shortness of breath, and wheezing. Shortly thereafter, upper respiratory conditions, including gastroesophageal reflux disease (GERD) and rhinosinusitis,1–3 became apparent and likewise were consistently reported across all WTC-exposed cohorts.2,4–6 Over time, questions were raised whether other conditions, such as obstructive sleep apnea (OSA), were also associated with WTC exposure. Biologic plausibility for a relationship between WTC exposure and OSA exists and is based on the known association between OSA and organic solvents,7 which were found at the WTC site.8 Alternatively, anecdotal observations linking OSA to WTC exposure could be the result of cofactors with known high prevalence in this cohort, which include obesity, GERD, and rhinosinusitis. Our previous study of WTC-exposed Fire Department of the City of New York (FDNY) firefighters showed an association beFrom the Department of Medicine (Ms Glaser, Dr Shah, Ms Zeig-Owens, Dr Appel, and Ms Weakley), Montefiore Medical Center, Bronx, NY; Bureau of Health Services (Ms Glaser, Ms Zeig-Owens, Ms Jaber, Ms Weakley, Dr Kelly, and Dr Prezant), Fire Department of the City of New York, Brooklyn, NY; Department of Epidemiology and Population Health (Drs Webber, Hall, and Cohen), Montefiore Medical Center and Albert Einstein College of Medicine, Bronx, NY; Department of Pulmonary Medicine (Drs Shah, Appel, and Prezant), Montefiore Medical Center and Albert Einstein College of Medicine, Bronx, NY; and Pulmonary, Critical Care, and Sleep Medicine Department (Dr Shulman), ProHEALTH Care Associates, LLP, Lake Success, NY. The authors declare no conflicts of interest. This study (10-03-064E) was approved by the Institutional Review Board at Montefiore Medical Center, Bronx, NY. Address correspondence to: Mayris P. Webber, DrPH, Bureau of Health Services, Fire Department of the City of New York, 9 Metrotech Center, Brooklyn, NY 11201 ([email protected]). C 2014 by American College of Occupational and Environmental Copyright Medicine DOI: 10.1097/JOM.0000000000000283
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tween symptoms of GERD and rhinosinusitis and high risk for OSA, as measured by the Berlin9 sleep questionnaire, and found a dose–response relationship with WTC exposure (early high exposure vs later low exposure).10 This study was symptom-based and therefore did not include diagnostic testing for OSA, GERD, or rhinosinusitis.10 Confirmation of our findings in other WTC-exposed cohorts has been lacking, with most studies failing to find associations between upper airway symptoms (GERD or rhinosinusitis) and OSA11,12 or between OSA and WTC exposure (exposed vs unexposed).11–13 Therefore, considerable uncertainty remains as to whether risk factors for OSA include WTC exposure or upper airway conditions.14,15 Obstructive sleep apnea is a chronic disorder characterized by complete (apnea) or partial (hypopnea) obstructions of breathing during sleep. Obstructive sleep apnea is characterized by cyclical oxygen desaturation, sleep fragmentation, arousals from sleep, and increased sympathetic activity. Obstructive sleep apnea is an important disease to detect and treat as it is associated with depressed mood, irritability, cognitive dysfunction,14 impaired glucose metabolism,16 hypertension,17,18 coronary heart disease,19,20 cerebrovascular disease,21,22 and an increased cancer mortality risk.23 Known risk factors for OSA include male sex, increasing age, and a body mass index (BMI) of 30 kg/m2 or more.14,22,24 In non–WTCexposed populations, it remains controversial whether OSA prevalence is increased in patients with upper airway conditions. Some studies have shown GERD25,26 and chronic rhinosinusitis (hereafter referred to as rhinosinusitis)27,28 to be significantly associated with an increased prevalence of OSA, whereas others have not.29,30 This study had two primary aims: (1) to determine the proportion of polysomnogram-confirmed diagnoses of OSA in FDNYWTC-exposed first responders at increased risk for OSA; and (2) to examine the relationship between polysomnogram-diagnosed OSA, WTC exposure, and physician-diagnosed GERD or physiciandiagnosed rhinosinusitis using FDNY medical records.
METHODS The FDNY Bureau of Health Services performs periodic health evaluations on FDNY firefighters and emergency medical service personnel, every 12 to 18 months. These monitoring examinations include both physician examinations and, since 2001, selfadministered physical and mental health questionnaires. This study (10-03-064E) was approved by the Institutional Review Board at Montefiore Medical Center (MMC), Bronx, New York. Oral consent was obtained from every participant.
Participants The source population consisted of male FDNY firefighters and emergency medical service workers who first arrived at the WTC site within the first 2 weeks after September 11, 2001, and who completed polysomnography, at no cost to them, between September 24, 2010, and September 23, 2012. We obtained the final population in two ways. The first group of individuals (n = 1430), which we call the targeted outreach group, was recruited, by mail, to receive a polysomnogram, on the basis of having known OSA risk factors (eg, snoring, excessive daytime fatigue, and an elevated BMI between 30 and 40 kg/m2 ). The second group was a convenience sample JOEM r Volume 56, Number 10S, October 2014
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(n = 398) of individuals who were prescribed a polysomnography by their FDNY treating physician on the basis of clinical indications, which may or may not have included an elevated BMI. We excluded data from persons diagnosed with polysomnogram-confirmed OSA before September 24, 2010.
Data Sources We obtained demographic data from the FDNY employee database; WTC exposure information from self-administered physical health questionnaires; FDNY physician diagnoses and diagnostic test information (polysomnography, upper endoscopy, sinus CT) from the FDNY electronic medical record; and prescription drug data from the FDNY pharmacy claims database. We calculated the BMI31 from measured heights and weights on the day of their last monitoring examination before the start date of the study. Physician visits, diagnostic tests, medications, and, when needed, OSA treatment (positive-pressure breathing) were at no cost to FDNY WTC-exposed participants.
Questionnaire Data We used data from the first post-September 11, 2001, questionnaire to obtain exposure to the WTC site on September 11, 2001. We compared this group with those who arrived any time thereafter, until September 24, 2001. Smoking status (ever/never) was abstracted from the most recent questionnaire completed by the patient.
FDNY Physician Diagnoses and Prescription Databases We searched the FDNY databases for FDNY physician diagnoses as well as condition-specific prescribed medications to assign upper respiratory condition categories (GERD, rhinosinusitis, comorbid GERD and rhinosinusitis, and neither). To be classified as having “confirmed” GERD or rhinosinusitis, each participant had to have had either an FDNY physician diagnosis, documented on at least two separate visits since September 11, 2001, or to have filled prescription medications consistent with either of these diagnoses. FDNY physicians receive instruction in diagnosing and treating respiratory diseases and are trained to use the same diagnostic criteria.32,33 Examining physicians selected diagnoses after integrating the history, physical examination, response to medication and, when clinically indicated, upper gastrointestinal (GI) endoscopy, laryngoscopy, and sinus CT imaging. GERD medications included proton pump inhibitors, histamine H2 -receptor antagonists, or promotility agents. Rhinosinusitis medications included nasal corticosteroids, decongestants, antihistamines, or saline rinses.
Sleep Studies Polysomnography was performed at several community sleep laboratories—all independent of the coordinating institutions MMC and FDNY. Standard polysomnography was performed with three electroencephalography electrodes, electrooculography, chin electromyography, pressure transducer to measure airflow through the nose, a thermistor for the measurement of airflow through the mouth, pulse oximetry for the measurement of oxygen saturation, piezoelectric respiratory signals for the measurement of chest and abdominal movement, and anterior tibialis electromyography. Apneas, hypopneas, and the apnea–hypopnea index (AHI) were determined using standard scoring criteria from the American Academy of Sleep Medicine.34,35 The AHI was used to create an ordinal variable for OSA, with “none” if the AHI was less than five events per hour of sleep, “mild” with an AHI of 5 to less than 15 episodes per hour of sleep, “moderate” with an AHI of 15 to less than 30 episodes per hour of sleep, and “severe” with an AHI of 30 episodes or more per hour of sleep. When split-night sleep studies were conducted, the
Obstructive Sleep Apnea and World Trade Center Exposure
AHI was determined using the diagnostic portion of the study. In the treatment portion of the study, continuous positive airway pressure therapy was applied to attenuate sleep-disordered breathing. We note that most of the polysomnograms in this study were split-night studies, likely a result of the inclusion criteria selecting high-risk OSA participants.
Statistical Analyses Chi-squared or t tests were used to compare the targeted outreach group with the convenience sample. Descriptive statistics are reported as means ± standard deviations or medians (interquartile range), as appropriate. Within the targeted outreach group, we also compared the group of participants with a polysomnography result with those who were invited but did not accept polysomnography using chi-squared or t test, as appropriate. Diagnoses of OSA were made using the AHI determined from polysomnography, as described earlier.11 Diagnostic variables were mutually exclusive categories of GERD only, rhinosinusitis only, comorbid GERD and rhinosinusitis, and neither condition. Unadjusted and adjusted associations between a diagnosis of OSA and the level of exposure to the WTC site, BMI, age, smoking status, and categorical condition variables (GERD, rhinosinusitis, comorbid, and neither) were tested using nominal polytomous logistic regression. Variables that were associated with OSA at P < 0.10 were included in an adjusted model. We performed a sensitivity analysis to confirm the reliability of the FDNY physician diagnoses by using information from GI endoscopy or sinus CT scans. Data were analyzed using SAS, version 9.3 (SAS Institute, Cary, NC).
RESULTS We obtained polysomnogram results from 636 of the 698 (91%) FDNY members who underwent polysomnography during the study period—398 from the convenience sample and 238 from the targeted sample. Of the 636 participants, 80.8% (n = 514) were diagnosed with OSA on the basis of the results of polysomnography. The overall median AHI was 21, with an interquartile range from 7.4 to 44.2 (Table 1). There were no meaningful differences between the targeted and convenience groups in smoking status, arrival time to the WTC, mean age at the time of polysomnography, mean BMI, and percentage with OSA. There was a small, nonsignificant difference in proportion retired by groups (58.4% of the targeted compared with 65.8% of the convenience sample; P = 0.06). As the groups were generally similar, we present combined analyses (n = 636). We compared the baseline characteristics of this study sample with the general FDNY population who did not receive polysomnography (Table 2). Those with polysomnography had a higher proportion of subjects who arrived at the WTC on the first day, September 11, 2001 (71.1% vs 63.5%; P < 0.0001). The mean age of the polysomnography-tested population was 51.5 ± 7.9 years, which was
TABLE 1. Polysomnography Results (n = 636) OSA Diagnosis None Mild Moderate Severe Total
n (%)
Median AHI (IQR)
122 (19.18) 126 (19.81) 125 (19.65) 263 (41.35) 636
1.0 (0.0–2.2) 10.0 (7.0–11.0) 20.0 (17.8–24.5) 50.0 (39.0–70.0) 21.0 (7.4–44.2)
AHI, apnea–hypopnea index; IQR, interquartile range; OSA, obstructive sleep apnea.
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sociated with moderate and severe OSA in adjusted and unadjusted models, but did not attain statistical significance in mild OSA models. There was no association between BMI and a GERD diagnosis (odds ratio, 0.8; 95% confidence interval, 0.3 to 2.1). We performed a sensitivity analysis to evaluate the reliability of FDNY medical record diagnoses of GERD or rhinosinusitis in relation to results from GI endoscopy (GERD) or sinus CT scan results. We found that, in this study population, almost 45% of those with GERD diagnoses in the medical record had an endoscopy, and that 99% of those with an endoscopy were diagnosed with GERD. Regarding rhinosinusitis, we found that 52% of those with rhinosinusitis diagnoses in the medical record received a sinus CT scan, and that 91% of those with a sinus CT scan were diagnosed with rhinosinusitis.
TABLE 2. Characteristics of the Patient Population Who Had Polysomnography (n = 636) Characteristic Mean age, yrs Work status Fire EMS Retired BMI, kg/m2 * 30 to ≤35 >35 to ≤40 Exposure to the WTC Arrived on September 11, 2001 Arrived between September 12, 2001, and September 24, 2001 Smoking status Ever Never Disease category† Neither GERD Rhinosinusitis Comorbid
n (%) or Mean (SD) 51.5 (7.9) 627 (98.6) 9 (1.4) 400 (62.9) 211 (33.7) 308 (49.1) 108 (17.2)
DISCUSSION 452 (71.1) 184 (28.9)
258 (40.6) 378 (59.4) 80 (12.6) 191 (30.0) 37 (5.8) 328 (51.6)
*Missing BMI in nine patients. †Disease categories are mutually exclusive. BMI, body mass index; EMS, emergency medical service; GERD, gastroesophageal reflux disease; SD, standard deviation; WTC, World Trade Center.
not different from the general FDNY population (P = 0.8). There was also no significant difference in the proportion of ever/never smokers (P = 0.6). Our tested group had a higher percentage of firefighters (98.6% vs 88.6%, respectively) and more FDNY retirees (62.9% vs 56.5%, respectively). Although the tested group had a statistically significantly higher mean BMI than the FDNY population (31.8 kg/m2 vs 29.7 kg/m2 ; P < 0.0001), the difference was clinically unimportant. Table 3 shows the prevalence of OSA by confirmed upper respiratory diagnoses. Of the 191 participants with GERD only, 40.8% had severe OSA. Of those with rhinosinusitis only (n = 37), 32.4% had severe OSA. Finally, among those with comorbid GERD and rhinosinusitis (n = 328), 43.9% were diagnosed with severe OSA. Using nominal polytomous logistic regression (Table 4), we examined unadjusted and adjusted associations between outcomes of polysomnography-confirmed OSA (mild, moderate, or severe OSA) and arrival at the WTC disaster site on September 11, 2001, upper respiratory diagnoses, BMI, age (in 5-year increments), and smoking status. The association between early WTC exposure and OSA was not significant in univariate models. In the adjusted models, all odds ratios were above 1, and in association with an outcome of severe OSA, conferred an almost twofold risk (odds ratio, 1.91; 95% confidence interval, 1.15 to 3.17). As expected, we also found that the BMI was directly and significantly associated with OSA. In the adjusted severe OSA model, those with a BMI of 35 to 40 kg/m2 had almost six times the odds compared with those with a BMI of less than 30 kg/m2 . In all unadjusted and adjusted models, those with a diagnosis of GERD alone were more than twice as likely to have OSA, and this was statistically significant for mild, moderate, and severe OSA. Comorbid GERD and rhinosinusitis were similarly asS32
The major findings of this study were the following: (1) those with the highest level of WTC exposure, arriving at the WTC site on September 11, 2001, were more likely to be diagnosed with severe OSA compared with those who experienced lower-level exposure; (2) all OSA outcomes were significantly associated with physician-diagnosed GERD; (3) similar associations between OSA and physician-diagnosed rhinosinusitis were not observed, although this may have been due to the lack of power; and (4) polysomnography-confirmed OSA was present in more than 80% of those tested. Unlike prior studies,11 we found that in adjusted models, those with the highest level of exposure to the WTC disaster were more likely to be diagnosed with OSA, an association that was statistically significant for those with severe OSA. The association observed between OSA and WTC exposure could result from the chronic inflammation seen in many WTC patient populations. This inflammation can reduce the diameter of the upper airway, which can lead to apneas and hypopneas as seen in patients with OSA.36 Regarding the strong association between OSA and GERD, some prior studies, unrelated to WTC exposure, have shown GERD to be a significant risk factor for increased prevalence of OSA,25,26 whereas others have not.29 The association we observed between OSA and GERD could result directly from narrowing of the upper airway because of chronic inflammation/edema, from chronic exposure to acid vapors arising from the gastroesophageal tract, and/or from the actual reflux of gastric contents into the upper airway when significant negative intrathoracic pressures are generated during apnea events. Because this study was cross-sectional in nature, we could not assess the temporal relationship between OSA and GERD. We explored the role of obesity as a potential confounder of the GERD and OSA association. A higher BMI was associated with higher odds of an OSA diagnosis, which was expected as the BMI is a known risk factor for OSA.22 Nevertheless, we found no significant association between the BMI and a GERD diagnosis. Hence, the association between OSA and GERD seems to be independent of the level of obesity, making it unlikely that GERD was acting as a surrogate for the BMI. We did not find significant associations between OSA and rhinosinusitis, but did find that comorbid GERD and rhinosinusitis were significantly associated with moderate and severe OSA, possibly because of an interaction between the upper airway resistance seen in rhinosinusitis and GERD-induced narrowing of the upper airway.27,37 The nonsignificance of the association of rhinosinusitis alone with OSA is consistent with at least one study unrelated to WTC exposure,30 but could also be due to inadequate statistical power as only 37 patients had rhinosinusitis without GERD. Yet, the fact that those with comorbid GERD and rhinosinusitis did not have a stronger association with OSA than GERD alone argues that rhinosinusitis, even if powered adequately, would not have been an important factor.
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TABLE 3. Prevalence of OSA by FDNY Physician-Diagnosed Disease Category Disease Category*
OSA Diagnosis None Mild Moderate Severe
Neither (n = 80) n (%)
GERD (n = 191) n (%)
Rhinosinusitis (n = 37) n (%)
Comorbid (n = 328) n (%)
26 (32.50) 16 (20.00) 9 (11.25) 29 (36.25)
26 (13.61) 40 (20.94) 47 (24.61) 78 (40.84)
11 (29.73) 8 (21.62) 6 (16.22) 12 (32.43)
59 (17.99) 62 (18.90) 63 (19.21) 144 (43.90)
*Disease categories are mutually exclusive. FDNY, Fire Department of the City of New York; GERD, gastroesophageal reflux disease; OSA, obstructive sleep apnea.
TABLE 4. Unadjusted and Adjusted Associations With Mild, Moderate, or Severe OSA* Unadjusted
BMI, kg/m2 >30 to ≤35 >35 to ≤40§ Age Ever smoker¶ Diagnosis GERD Rhinosinusitis Comorbid Exposure—arrived on September 11
Adjusted
Mild OSA† OR‡ (95% CI‡)
Moderate OSA† OR‡ (95% CI‡)
Severe OSA† OR‡ (95% CI‡)
Mild OSA† OR‡ (95% CI‡)
Moderate OSA† OR‡ (95% CI‡)
Severe OSA† OR‡ (95% CI‡)
1.16 (0.68–1.98) 1.97 (0.79–4.87) 1.07 (0.91–1.26) 0.80 (0.48–1.33)
1.12 (0.65–1.92) 2.70 (1.12–6.48) 1.16 (0.98–1.36) 0.93 (0.56–1.54)
1.71 (1.06–2.75) 5.35 (2.43–11.75) 1.22 (1.06–1.40) 1.02 (0.66–1.57)
1.16 (0.68–1.99) 2.08 (0.83–5.21) 1.10 (0.93–1.30) – (–)
1.11 (0.64–1.93) 2.91 (1.19–7.13) 1.17 (0.99–1.38) – (–)
1.70 (1.05–2.77) 5.90 (2.63–13.25) 1.30 (1.10–1.49) – (–)
2.50 (1.13–5.54) 1.18 (0.39–3.56) 1.71 (0.83–3.50) 1.22 (0.71–2.08)
5.22 (2.13–12.80) 1.58 (0.45–5.50) 3.09 (1.34–7.12) 1.00 (0.59–1.70)
2.69 (1.35–5.37) 0.98 (0.37–2.59) 2.19 (1.19–4.03) 1.57 (0.98–2.52)
2.47 (1.10–5.54) 1.14 (0.37–3.46) 1.69 (0.82–3.49) 1.29 (0.74–2.25)
5.28 (2.13–13.13) 1.25 (0.34–4.66) 3.07 (1.32–7.18) 1.14 (0.65–1.99)
2.75 (1.33–5.70) 0.95 (0.34–2.64) 2.31 (1.22–4.40) 1.91 (1.15–3.17)
*The final adjusted models did not adjust for smoking status. †Reference is no-diagnosed OSA. ‡Odds ratios and 95% confidence intervals were based on logistic regression. §Reference is a BMI of less than 30. Age is in 5-year increments. ¶Ever smokes versus never smokers. BMI, body mass index; CI, confidence interval; OR, odds ratio; OSA, obstructive sleep apnea.
Our sample of 636 men was composed of a targeted outreach group and a convenience sample. Although patients who presented to an FDNY physician for treatment/evaluation (convenience sample) had the higher risk of severe OSA (43.2%), 38.2% of the targeted outreach group who did not initiate treatment/evaluation were diagnosed with severe OSA, indicating under-recognition of high-risk status in this population who did not present for testing before study recruitment. This under-recognition is of particular importance as all participants had unrestricted access to no-cost health care services at the FDNY-WTC Health Program and were known to be at increased risk for OSA (on the basis of male sex, mean age >40 years, and the elevated mean BMI). It is medically important to identify OSA as it is well known that OSA can lead to increased morbidity,22 mortality,20,21 and health care costs as well as have adverse effects on the quality of life.14 Several limitations should be considered when interpreting this study’s findings. First, we did not have a non–WTC-exposed comparison group, which may have led to under-estimates of the relationship between OSA and WTC exposure. Second, we used a convenience sample, limiting the generalizability of our results. Those who had polysomnography had a higher BMI and were somewhat more likely to be retired than the general male FDNY population. Most of our sleep studies were split-night studies performed in
community sleep laboratories. The current American Academy of Sleep Medicine practice parameters support splitting studies when the AHI during the first half of the night is 20 to 40 events per hour of sleep.38 We noted, on several occasions, that split-night testing was performed even when apnea severity was at most mild, the diagnostic portion of the study was less than 90 minutes, and rapid eye movement sleep was not captured. Thus, it is possible that some of the sleep studies were prematurely split; as a result the resultant AHI may have under- or over-estimated OSA severity. Nevertheless, there is emerging evidence that the first hours of a sleep study can accurately identify those with OSA using an AHI threshold of five events per hour.39 This study has several strengths. We conducted full-night attended polysomnography to diagnose OSA instead of commonly used screening tools such as the Berlin OSA screening questionnaire or portable polysomnography. We evaluated an important relationship between OSA, early WTC exposure, and physician-diagnosed upper respiratory diseases in a population of September 11, 2001, first responders, directly capturing physician diagnosis from the FDNY medical record instead of relying on self-reported diagnoses of these conditions. Of those with diagnostic testing (endoscopy or sinus CT), almost all were confirmed, indicating high reliability of FDNY physician diagnoses for GERD and rhinosinusitis. Clinically,
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our findings may lead to increased OSA screening as OSA was common in this high-risk population. In summary, this study demonstrated a statistically significant association between severe OSA and WTC exposure, while also reporting significant associations between OSA and other conditions that are prevalent in this population of FDNY WTC-exposed first responders—GERD and comorbid GERD/rhinosinusitis. Importantly, these associations were independent of the degree of obesity. Rhinosinusitis diagnoses, although common in this population and among those with OSA, did not seem to be independently associated with OSA, after adjusting for age and obesity. On the basis of our findings, we recommend clinical evaluation including polysomnography for any patient with high WTC exposure, risk factors for OSA, and a physician diagnosis of GERD or comorbid GERD and rhinosinusitis.
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16. Punjabi NM, Shahar E, Redline S, Gottlieb DJ, Givelber R, Resnick HE. Sleep-disordered breathing, glucose intolerance, and insulin resistance: the Sleep Heart Health Study. Am J Epidemiol. 2004;160:521–530. 17. Peppard PE, Young T, Palta M, Skatrud J. Prospective study of the association between sleep-disordered breathing and hypertension. N Engl J Med. 2000;342:1378–1384. 18. Young T, Peppard P, Palta M, et al. Population-based study of sleep-disordered breathing as a risk factor for hypertension. Arch Intern Med. 1997;157:1746– 1752. 19. Peker Y, Kraiczi H, Hedner J, Loth S, Johansson A, Bende M. An independent association between obstructive sleep apnoea and coronary artery disease. Eur Respir J. 1999;14:179–184. 20. Shah NA, Yaggi HK, Concato J, Mohsenin V. Obstructive sleep apnea as a risk factor for coronary events or cardiovascular death. Sleep Breath. 2010;14:131– 136. 21. Yaggi HK, Concato J, Kernan WN, Lichtman JH, Brass LM, Mohsenin V. Obstructive sleep apnea as a risk factor for stroke and death. N Engl J Med. 2005;353:2034–41. 22. Young T, Peppard PE, Gottlieb DJ. Epidemiology of obstructive sleep apnea: a population health perspective. Am J Respir Crit Care Med. 2002;165:1217– 39. 23. Nieto FJ, Peppard PE, Young T, Finn L, Hla KM, Farre R. Sleep disordered breathing and cancer mortality: results from the Wisconsin Sleep Cohort Study. Am J Respir Crit Care Med. 2012;186:190–194. 24. Young T, Peppard PE, Taheri S. Excess weight and sleep-disordered breathing. J Appl Physiol. 2005;99:1592–1599. 25. Penzel T, Becker HF, Brandenburg U, Labunski T, Pankow W, Peter JH. Arousal in patients with gastro-oesophageal reflux and sleep apnoea. Eur Respir J. 1999;14:1266–1270. 26. Shepherd KL, James AL, Musk AW, Hunter ML, Hillman DR, Eastwood PR. Gastro-oesophageal reflux symptoms are related to the presence and severity of obstructive sleep apnoea. J Sleep Res. 2011;20:241–249. 27. McNicholas WT, Tarlo S, Cole P, et al. Obstructive apneas during sleep in patients with seasonal allergic rhinitis. Am Rev Respir Dis. 1982;126:625–628. 28. Kalpaklioglu AF, Kavut AB, Ekici M. Allergic and nonallergic rhinitis: the threat for obstructive sleep apnea. Ann Allergy Asthma Immunol. 2009;103:20–25. 29. Kim HN, Vorona RD, Winn MP, Doviak M, Johnson DA, Ware JC. Symptoms of gastro-oesophageal reflux disease and the severity of obstructive sleep apnoea syndrome are not related in sleep disorders center patients. Aliment Pharmacol Ther. 2005;21:1127–1133. 30. Staevska MT, Mandajieva MA, Dimitrov VD. Rhinitis and sleep apnea. Curr Allergy Asthma Rep. 2004;4:193–199. 31. CDC. Body Mass Index. Center for Disease Control and Prevention; 2011. 32. Mannino DM. Chronic obstructive pulmonary disease: definition and epidemiology. Respir Care. 2003;48:1185–1191; discussion 1191–1193. 33. Meltzer EO, Hamilos DL, Hadley JA, et al. Rhinosinusitis: establishing definitions for clinical research and patient care. J Allergy Clin Immunol. 2004;114:155–212. 34. Sleep-related breathing disorders in adults: recommendations for syndrome definition and measurement techniques in clinical research. The Report of an American Academy of Sleep Medicine Task Force. Sleep. 1999;22:667–689. 35. Epstein LJ, Kristo D, Strollo PJ Jr, et al. Clinical guideline for the evaluation, management and long-term care of obstructive sleep apnea in adults. J Clin Sleep Med. 2009;5:263–276. 36. Ryan CM, Bradley TD. Pathogenesis of obstructive sleep apnea. J Appl Physiol. 2005;99:2440–2450. 37. Demeter P, Pap A. The relationship between gastroesophageal reflux disease and obstructive sleep apnea. J Gastroenterol. 2004;39:815–820. 38. Littner M, Hirshkowitz M, Davila D, et al. Practice parameters for the use of auto-titrating continuous positive airway pressure devices for titrating pressures and treating adult patients with obstructive sleep apnea syndrome. An American Academy of Sleep Medicine report. Sleep. 2002;25:143–147. 39. Khawaja IS, Olson EJ, van der Walt C, et al. Diagnostic accuracy of split-night polysomnograms. J Clin Sleep Med 2010;6:357–362.
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Obstructive Sleep Apnea and World Trade Center Exposure Michelle S. Glaser, MPH, Neomi Shah, MD, Mayris P. Webber, DrPH, Rachel Zeig-Owens, MPH, Nadia Jaber, RPA-C, David W. Appel, MD, Charles B. Hall, PhD, Jessica Weakley, MPH, Hillel W. Cohen, DrPH, Lawrence Shulman, DO, Kerry Kelly, MD, and David Prezant, MD
Objectives: To describe the proportion of at-risk World Trade Center (WTC)exposed rescue/recovery workers with polysomnogram-confirmed obstructive sleep apnea (OSA) and examine the relationship between WTC exposure, physician-diagnosed gastroesophageal reflux disease (GERD), and rhinosinusitis and OSA. Methods: A total of 636 male participants completed polysomnography from September 24, 2010, to September 23, 2012. Obstructive sleep apnea was classified as mild, moderate, or severe. Associations were tested using nominal polytomous logistic regression. Results: Eighty-one percent of workers were diagnosed with OSA. Using logistic regression models, severe OSA was associated with WTC exposure on September 11, 2001 (odds ratio, 1.91; 95% confidence interval, 1.15 to 3.17), GERD (odds ratio, 2.75; 95% confidence interval, 1.33 to 5.70), and comorbid GERD/rhinosinusitis (odds ratio, 2.31; 95% confidence interval, 1.22 to 4.40). Conclusions: We found significant associations between severe OSA and WTC exposure, and with diseases prevalent in this population. Accordingly, we recommend clinical evaluation, including polysomnography, for patients with high WTC exposure, other OSA risk factors, and a physician diagnosis of GERD or comorbid GERD and rhinosinusitis.
H
undreds of studies have confirmed the relationship between work at the World Trade Center (WTC) disaster site and subsequent respiratory health issues. Lower respiratory conditions were quickly identified because of obvious symptoms of cough, shortness of breath, and wheezing. Shortly thereafter, upper respiratory conditions, including gastroesophageal reflux disease (GERD) and rhinosinusitis,1–3 became apparent and likewise were consistently reported across all WTC-exposed cohorts.2,4–6 Over time, questions were raised whether other conditions, such as obstructive sleep apnea (OSA), were also associated with WTC exposure. Biologic plausibility for a relationship between WTC exposure and OSA exists and is based on the known association between OSA and organic solvents,7 which were found at the WTC site.8 Alternatively, anecdotal observations linking OSA to WTC exposure could be the result of cofactors with known high prevalence in this cohort, which include obesity, GERD, and rhinosinusitis. Our previous study of WTC-exposed Fire Department of the City of New York (FDNY) firefighters showed an association beFrom the Department of Medicine (Ms Glaser, Dr Shah, Ms Zeig-Owens, Dr Appel, and Ms Weakley), Montefiore Medical Center, Bronx, NY; Bureau of Health Services (Ms Glaser, Ms Zeig-Owens, Ms Jaber, Ms Weakley, Dr Kelly, and Dr Prezant), Fire Department of the City of New York, Brooklyn, NY; Department of Epidemiology and Population Health (Drs Webber, Hall, and Cohen), Montefiore Medical Center and Albert Einstein College of Medicine, Bronx, NY; Department of Pulmonary Medicine (Drs Shah, Appel, and Prezant), Montefiore Medical Center and Albert Einstein College of Medicine, Bronx, NY; and Pulmonary, Critical Care, and Sleep Medicine Department (Dr Shulman), ProHEALTH Care Associates, LLP, Lake Success, NY. The authors declare no conflicts of interest. This study (10-03-064E) was approved by the Institutional Review Board at Montefiore Medical Center, Bronx, NY. Address correspondence to: Mayris P. Webber, DrPH, Bureau of Health Services, Fire Department of the City of New York, 9 Metrotech Center, Brooklyn, NY 11201 ([email protected]). C 2014 by American College of Occupational and Environmental Copyright Medicine DOI: 10.1097/JOM.0000000000000283
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tween symptoms of GERD and rhinosinusitis and high risk for OSA, as measured by the Berlin9 sleep questionnaire, and found a dose–response relationship with WTC exposure (early high exposure vs later low exposure).10 This study was symptom-based and therefore did not include diagnostic testing for OSA, GERD, or rhinosinusitis.10 Confirmation of our findings in other WTC-exposed cohorts has been lacking, with most studies failing to find associations between upper airway symptoms (GERD or rhinosinusitis) and OSA11,12 or between OSA and WTC exposure (exposed vs unexposed).11–13 Therefore, considerable uncertainty remains as to whether risk factors for OSA include WTC exposure or upper airway conditions.14,15 Obstructive sleep apnea is a chronic disorder characterized by complete (apnea) or partial (hypopnea) obstructions of breathing during sleep. Obstructive sleep apnea is characterized by cyclical oxygen desaturation, sleep fragmentation, arousals from sleep, and increased sympathetic activity. Obstructive sleep apnea is an important disease to detect and treat as it is associated with depressed mood, irritability, cognitive dysfunction,14 impaired glucose metabolism,16 hypertension,17,18 coronary heart disease,19,20 cerebrovascular disease,21,22 and an increased cancer mortality risk.23 Known risk factors for OSA include male sex, increasing age, and a body mass index (BMI) of 30 kg/m2 or more.14,22,24 In non–WTCexposed populations, it remains controversial whether OSA prevalence is increased in patients with upper airway conditions. Some studies have shown GERD25,26 and chronic rhinosinusitis (hereafter referred to as rhinosinusitis)27,28 to be significantly associated with an increased prevalence of OSA, whereas others have not.29,30 This study had two primary aims: (1) to determine the proportion of polysomnogram-confirmed diagnoses of OSA in FDNYWTC-exposed first responders at increased risk for OSA; and (2) to examine the relationship between polysomnogram-diagnosed OSA, WTC exposure, and physician-diagnosed GERD or physiciandiagnosed rhinosinusitis using FDNY medical records.
METHODS The FDNY Bureau of Health Services performs periodic health evaluations on FDNY firefighters and emergency medical service personnel, every 12 to 18 months. These monitoring examinations include both physician examinations and, since 2001, selfadministered physical and mental health questionnaires. This study (10-03-064E) was approved by the Institutional Review Board at Montefiore Medical Center (MMC), Bronx, New York. Oral consent was obtained from every participant.
Participants The source population consisted of male FDNY firefighters and emergency medical service workers who first arrived at the WTC site within the first 2 weeks after September 11, 2001, and who completed polysomnography, at no cost to them, between September 24, 2010, and September 23, 2012. We obtained the final population in two ways. The first group of individuals (n = 1430), which we call the targeted outreach group, was recruited, by mail, to receive a polysomnogram, on the basis of having known OSA risk factors (eg, snoring, excessive daytime fatigue, and an elevated BMI between 30 and 40 kg/m2 ). The second group was a convenience sample JOEM r Volume 56, Number 10S, October 2014
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(n = 398) of individuals who were prescribed a polysomnography by their FDNY treating physician on the basis of clinical indications, which may or may not have included an elevated BMI. We excluded data from persons diagnosed with polysomnogram-confirmed OSA before September 24, 2010.
Data Sources We obtained demographic data from the FDNY employee database; WTC exposure information from self-administered physical health questionnaires; FDNY physician diagnoses and diagnostic test information (polysomnography, upper endoscopy, sinus CT) from the FDNY electronic medical record; and prescription drug data from the FDNY pharmacy claims database. We calculated the BMI31 from measured heights and weights on the day of their last monitoring examination before the start date of the study. Physician visits, diagnostic tests, medications, and, when needed, OSA treatment (positive-pressure breathing) were at no cost to FDNY WTC-exposed participants.
Questionnaire Data We used data from the first post-September 11, 2001, questionnaire to obtain exposure to the WTC site on September 11, 2001. We compared this group with those who arrived any time thereafter, until September 24, 2001. Smoking status (ever/never) was abstracted from the most recent questionnaire completed by the patient.
FDNY Physician Diagnoses and Prescription Databases We searched the FDNY databases for FDNY physician diagnoses as well as condition-specific prescribed medications to assign upper respiratory condition categories (GERD, rhinosinusitis, comorbid GERD and rhinosinusitis, and neither). To be classified as having “confirmed” GERD or rhinosinusitis, each participant had to have had either an FDNY physician diagnosis, documented on at least two separate visits since September 11, 2001, or to have filled prescription medications consistent with either of these diagnoses. FDNY physicians receive instruction in diagnosing and treating respiratory diseases and are trained to use the same diagnostic criteria.32,33 Examining physicians selected diagnoses after integrating the history, physical examination, response to medication and, when clinically indicated, upper gastrointestinal (GI) endoscopy, laryngoscopy, and sinus CT imaging. GERD medications included proton pump inhibitors, histamine H2 -receptor antagonists, or promotility agents. Rhinosinusitis medications included nasal corticosteroids, decongestants, antihistamines, or saline rinses.
Sleep Studies Polysomnography was performed at several community sleep laboratories—all independent of the coordinating institutions MMC and FDNY. Standard polysomnography was performed with three electroencephalography electrodes, electrooculography, chin electromyography, pressure transducer to measure airflow through the nose, a thermistor for the measurement of airflow through the mouth, pulse oximetry for the measurement of oxygen saturation, piezoelectric respiratory signals for the measurement of chest and abdominal movement, and anterior tibialis electromyography. Apneas, hypopneas, and the apnea–hypopnea index (AHI) were determined using standard scoring criteria from the American Academy of Sleep Medicine.34,35 The AHI was used to create an ordinal variable for OSA, with “none” if the AHI was less than five events per hour of sleep, “mild” with an AHI of 5 to less than 15 episodes per hour of sleep, “moderate” with an AHI of 15 to less than 30 episodes per hour of sleep, and “severe” with an AHI of 30 episodes or more per hour of sleep. When split-night sleep studies were conducted, the
Obstructive Sleep Apnea and World Trade Center Exposure
AHI was determined using the diagnostic portion of the study. In the treatment portion of the study, continuous positive airway pressure therapy was applied to attenuate sleep-disordered breathing. We note that most of the polysomnograms in this study were split-night studies, likely a result of the inclusion criteria selecting high-risk OSA participants.
Statistical Analyses Chi-squared or t tests were used to compare the targeted outreach group with the convenience sample. Descriptive statistics are reported as means ± standard deviations or medians (interquartile range), as appropriate. Within the targeted outreach group, we also compared the group of participants with a polysomnography result with those who were invited but did not accept polysomnography using chi-squared or t test, as appropriate. Diagnoses of OSA were made using the AHI determined from polysomnography, as described earlier.11 Diagnostic variables were mutually exclusive categories of GERD only, rhinosinusitis only, comorbid GERD and rhinosinusitis, and neither condition. Unadjusted and adjusted associations between a diagnosis of OSA and the level of exposure to the WTC site, BMI, age, smoking status, and categorical condition variables (GERD, rhinosinusitis, comorbid, and neither) were tested using nominal polytomous logistic regression. Variables that were associated with OSA at P < 0.10 were included in an adjusted model. We performed a sensitivity analysis to confirm the reliability of the FDNY physician diagnoses by using information from GI endoscopy or sinus CT scans. Data were analyzed using SAS, version 9.3 (SAS Institute, Cary, NC).
RESULTS We obtained polysomnogram results from 636 of the 698 (91%) FDNY members who underwent polysomnography during the study period—398 from the convenience sample and 238 from the targeted sample. Of the 636 participants, 80.8% (n = 514) were diagnosed with OSA on the basis of the results of polysomnography. The overall median AHI was 21, with an interquartile range from 7.4 to 44.2 (Table 1). There were no meaningful differences between the targeted and convenience groups in smoking status, arrival time to the WTC, mean age at the time of polysomnography, mean BMI, and percentage with OSA. There was a small, nonsignificant difference in proportion retired by groups (58.4% of the targeted compared with 65.8% of the convenience sample; P = 0.06). As the groups were generally similar, we present combined analyses (n = 636). We compared the baseline characteristics of this study sample with the general FDNY population who did not receive polysomnography (Table 2). Those with polysomnography had a higher proportion of subjects who arrived at the WTC on the first day, September 11, 2001 (71.1% vs 63.5%; P < 0.0001). The mean age of the polysomnography-tested population was 51.5 ± 7.9 years, which was
TABLE 1. Polysomnography Results (n = 636) OSA Diagnosis None Mild Moderate Severe Total
n (%)
Median AHI (IQR)
122 (19.18) 126 (19.81) 125 (19.65) 263 (41.35) 636
1.0 (0.0–2.2) 10.0 (7.0–11.0) 20.0 (17.8–24.5) 50.0 (39.0–70.0) 21.0 (7.4–44.2)
AHI, apnea–hypopnea index; IQR, interquartile range; OSA, obstructive sleep apnea.
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sociated with moderate and severe OSA in adjusted and unadjusted models, but did not attain statistical significance in mild OSA models. There was no association between BMI and a GERD diagnosis (odds ratio, 0.8; 95% confidence interval, 0.3 to 2.1). We performed a sensitivity analysis to evaluate the reliability of FDNY medical record diagnoses of GERD or rhinosinusitis in relation to results from GI endoscopy (GERD) or sinus CT scan results. We found that, in this study population, almost 45% of those with GERD diagnoses in the medical record had an endoscopy, and that 99% of those with an endoscopy were diagnosed with GERD. Regarding rhinosinusitis, we found that 52% of those with rhinosinusitis diagnoses in the medical record received a sinus CT scan, and that 91% of those with a sinus CT scan were diagnosed with rhinosinusitis.
TABLE 2. Characteristics of the Patient Population Who Had Polysomnography (n = 636) Characteristic Mean age, yrs Work status Fire EMS Retired BMI, kg/m2 * 30 to ≤35 >35 to ≤40 Exposure to the WTC Arrived on September 11, 2001 Arrived between September 12, 2001, and September 24, 2001 Smoking status Ever Never Disease category† Neither GERD Rhinosinusitis Comorbid
n (%) or Mean (SD) 51.5 (7.9) 627 (98.6) 9 (1.4) 400 (62.9) 211 (33.7) 308 (49.1) 108 (17.2)
DISCUSSION 452 (71.1) 184 (28.9)
258 (40.6) 378 (59.4) 80 (12.6) 191 (30.0) 37 (5.8) 328 (51.6)
*Missing BMI in nine patients. †Disease categories are mutually exclusive. BMI, body mass index; EMS, emergency medical service; GERD, gastroesophageal reflux disease; SD, standard deviation; WTC, World Trade Center.
not different from the general FDNY population (P = 0.8). There was also no significant difference in the proportion of ever/never smokers (P = 0.6). Our tested group had a higher percentage of firefighters (98.6% vs 88.6%, respectively) and more FDNY retirees (62.9% vs 56.5%, respectively). Although the tested group had a statistically significantly higher mean BMI than the FDNY population (31.8 kg/m2 vs 29.7 kg/m2 ; P < 0.0001), the difference was clinically unimportant. Table 3 shows the prevalence of OSA by confirmed upper respiratory diagnoses. Of the 191 participants with GERD only, 40.8% had severe OSA. Of those with rhinosinusitis only (n = 37), 32.4% had severe OSA. Finally, among those with comorbid GERD and rhinosinusitis (n = 328), 43.9% were diagnosed with severe OSA. Using nominal polytomous logistic regression (Table 4), we examined unadjusted and adjusted associations between outcomes of polysomnography-confirmed OSA (mild, moderate, or severe OSA) and arrival at the WTC disaster site on September 11, 2001, upper respiratory diagnoses, BMI, age (in 5-year increments), and smoking status. The association between early WTC exposure and OSA was not significant in univariate models. In the adjusted models, all odds ratios were above 1, and in association with an outcome of severe OSA, conferred an almost twofold risk (odds ratio, 1.91; 95% confidence interval, 1.15 to 3.17). As expected, we also found that the BMI was directly and significantly associated with OSA. In the adjusted severe OSA model, those with a BMI of 35 to 40 kg/m2 had almost six times the odds compared with those with a BMI of less than 30 kg/m2 . In all unadjusted and adjusted models, those with a diagnosis of GERD alone were more than twice as likely to have OSA, and this was statistically significant for mild, moderate, and severe OSA. Comorbid GERD and rhinosinusitis were similarly asS32
The major findings of this study were the following: (1) those with the highest level of WTC exposure, arriving at the WTC site on September 11, 2001, were more likely to be diagnosed with severe OSA compared with those who experienced lower-level exposure; (2) all OSA outcomes were significantly associated with physician-diagnosed GERD; (3) similar associations between OSA and physician-diagnosed rhinosinusitis were not observed, although this may have been due to the lack of power; and (4) polysomnography-confirmed OSA was present in more than 80% of those tested. Unlike prior studies,11 we found that in adjusted models, those with the highest level of exposure to the WTC disaster were more likely to be diagnosed with OSA, an association that was statistically significant for those with severe OSA. The association observed between OSA and WTC exposure could result from the chronic inflammation seen in many WTC patient populations. This inflammation can reduce the diameter of the upper airway, which can lead to apneas and hypopneas as seen in patients with OSA.36 Regarding the strong association between OSA and GERD, some prior studies, unrelated to WTC exposure, have shown GERD to be a significant risk factor for increased prevalence of OSA,25,26 whereas others have not.29 The association we observed between OSA and GERD could result directly from narrowing of the upper airway because of chronic inflammation/edema, from chronic exposure to acid vapors arising from the gastroesophageal tract, and/or from the actual reflux of gastric contents into the upper airway when significant negative intrathoracic pressures are generated during apnea events. Because this study was cross-sectional in nature, we could not assess the temporal relationship between OSA and GERD. We explored the role of obesity as a potential confounder of the GERD and OSA association. A higher BMI was associated with higher odds of an OSA diagnosis, which was expected as the BMI is a known risk factor for OSA.22 Nevertheless, we found no significant association between the BMI and a GERD diagnosis. Hence, the association between OSA and GERD seems to be independent of the level of obesity, making it unlikely that GERD was acting as a surrogate for the BMI. We did not find significant associations between OSA and rhinosinusitis, but did find that comorbid GERD and rhinosinusitis were significantly associated with moderate and severe OSA, possibly because of an interaction between the upper airway resistance seen in rhinosinusitis and GERD-induced narrowing of the upper airway.27,37 The nonsignificance of the association of rhinosinusitis alone with OSA is consistent with at least one study unrelated to WTC exposure,30 but could also be due to inadequate statistical power as only 37 patients had rhinosinusitis without GERD. Yet, the fact that those with comorbid GERD and rhinosinusitis did not have a stronger association with OSA than GERD alone argues that rhinosinusitis, even if powered adequately, would not have been an important factor.
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Obstructive Sleep Apnea and World Trade Center Exposure
TABLE 3. Prevalence of OSA by FDNY Physician-Diagnosed Disease Category Disease Category*
OSA Diagnosis None Mild Moderate Severe
Neither (n = 80) n (%)
GERD (n = 191) n (%)
Rhinosinusitis (n = 37) n (%)
Comorbid (n = 328) n (%)
26 (32.50) 16 (20.00) 9 (11.25) 29 (36.25)
26 (13.61) 40 (20.94) 47 (24.61) 78 (40.84)
11 (29.73) 8 (21.62) 6 (16.22) 12 (32.43)
59 (17.99) 62 (18.90) 63 (19.21) 144 (43.90)
*Disease categories are mutually exclusive. FDNY, Fire Department of the City of New York; GERD, gastroesophageal reflux disease; OSA, obstructive sleep apnea.
TABLE 4. Unadjusted and Adjusted Associations With Mild, Moderate, or Severe OSA* Unadjusted
BMI, kg/m2 >30 to ≤35 >35 to ≤40§ Age Ever smoker¶ Diagnosis GERD Rhinosinusitis Comorbid Exposure—arrived on September 11
Adjusted
Mild OSA† OR‡ (95% CI‡)
Moderate OSA† OR‡ (95% CI‡)
Severe OSA† OR‡ (95% CI‡)
Mild OSA† OR‡ (95% CI‡)
Moderate OSA† OR‡ (95% CI‡)
Severe OSA† OR‡ (95% CI‡)
1.16 (0.68–1.98) 1.97 (0.79–4.87) 1.07 (0.91–1.26) 0.80 (0.48–1.33)
1.12 (0.65–1.92) 2.70 (1.12–6.48) 1.16 (0.98–1.36) 0.93 (0.56–1.54)
1.71 (1.06–2.75) 5.35 (2.43–11.75) 1.22 (1.06–1.40) 1.02 (0.66–1.57)
1.16 (0.68–1.99) 2.08 (0.83–5.21) 1.10 (0.93–1.30) – (–)
1.11 (0.64–1.93) 2.91 (1.19–7.13) 1.17 (0.99–1.38) – (–)
1.70 (1.05–2.77) 5.90 (2.63–13.25) 1.30 (1.10–1.49) – (–)
2.50 (1.13–5.54) 1.18 (0.39–3.56) 1.71 (0.83–3.50) 1.22 (0.71–2.08)
5.22 (2.13–12.80) 1.58 (0.45–5.50) 3.09 (1.34–7.12) 1.00 (0.59–1.70)
2.69 (1.35–5.37) 0.98 (0.37–2.59) 2.19 (1.19–4.03) 1.57 (0.98–2.52)
2.47 (1.10–5.54) 1.14 (0.37–3.46) 1.69 (0.82–3.49) 1.29 (0.74–2.25)
5.28 (2.13–13.13) 1.25 (0.34–4.66) 3.07 (1.32–7.18) 1.14 (0.65–1.99)
2.75 (1.33–5.70) 0.95 (0.34–2.64) 2.31 (1.22–4.40) 1.91 (1.15–3.17)
*The final adjusted models did not adjust for smoking status. †Reference is no-diagnosed OSA. ‡Odds ratios and 95% confidence intervals were based on logistic regression. §Reference is a BMI of less than 30. Age is in 5-year increments. ¶Ever smokes versus never smokers. BMI, body mass index; CI, confidence interval; OR, odds ratio; OSA, obstructive sleep apnea.
Our sample of 636 men was composed of a targeted outreach group and a convenience sample. Although patients who presented to an FDNY physician for treatment/evaluation (convenience sample) had the higher risk of severe OSA (43.2%), 38.2% of the targeted outreach group who did not initiate treatment/evaluation were diagnosed with severe OSA, indicating under-recognition of high-risk status in this population who did not present for testing before study recruitment. This under-recognition is of particular importance as all participants had unrestricted access to no-cost health care services at the FDNY-WTC Health Program and were known to be at increased risk for OSA (on the basis of male sex, mean age >40 years, and the elevated mean BMI). It is medically important to identify OSA as it is well known that OSA can lead to increased morbidity,22 mortality,20,21 and health care costs as well as have adverse effects on the quality of life.14 Several limitations should be considered when interpreting this study’s findings. First, we did not have a non–WTC-exposed comparison group, which may have led to under-estimates of the relationship between OSA and WTC exposure. Second, we used a convenience sample, limiting the generalizability of our results. Those who had polysomnography had a higher BMI and were somewhat more likely to be retired than the general male FDNY population. Most of our sleep studies were split-night studies performed in
community sleep laboratories. The current American Academy of Sleep Medicine practice parameters support splitting studies when the AHI during the first half of the night is 20 to 40 events per hour of sleep.38 We noted, on several occasions, that split-night testing was performed even when apnea severity was at most mild, the diagnostic portion of the study was less than 90 minutes, and rapid eye movement sleep was not captured. Thus, it is possible that some of the sleep studies were prematurely split; as a result the resultant AHI may have under- or over-estimated OSA severity. Nevertheless, there is emerging evidence that the first hours of a sleep study can accurately identify those with OSA using an AHI threshold of five events per hour.39 This study has several strengths. We conducted full-night attended polysomnography to diagnose OSA instead of commonly used screening tools such as the Berlin OSA screening questionnaire or portable polysomnography. We evaluated an important relationship between OSA, early WTC exposure, and physician-diagnosed upper respiratory diseases in a population of September 11, 2001, first responders, directly capturing physician diagnosis from the FDNY medical record instead of relying on self-reported diagnoses of these conditions. Of those with diagnostic testing (endoscopy or sinus CT), almost all were confirmed, indicating high reliability of FDNY physician diagnoses for GERD and rhinosinusitis. Clinically,
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our findings may lead to increased OSA screening as OSA was common in this high-risk population. In summary, this study demonstrated a statistically significant association between severe OSA and WTC exposure, while also reporting significant associations between OSA and other conditions that are prevalent in this population of FDNY WTC-exposed first responders—GERD and comorbid GERD/rhinosinusitis. Importantly, these associations were independent of the degree of obesity. Rhinosinusitis diagnoses, although common in this population and among those with OSA, did not seem to be independently associated with OSA, after adjusting for age and obesity. On the basis of our findings, we recommend clinical evaluation including polysomnography for any patient with high WTC exposure, risk factors for OSA, and a physician diagnosis of GERD or comorbid GERD and rhinosinusitis.
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