Obstructive Lung Disease in Children with Idiopathic Scoliosis Gary L. McPhail, MD1, Zarmina Ehsan, MD1, Sacha A. Howells, BA2, R. Paul Boesch, DO, MS3, Matthew C. Fenchel, MS1, Rhonda Szczesniak, PhD1, Viral Jain, MD4, Steven Agabegi, MD4, Peter Sturm, MD4, Eric Wall, MD4, and Greg J. Redding, MD5 Objective To measure the prevalence of obstructive lung disease (OLD) among patients undergoing preoperative pulmonary assessment for idiopathic scoliosis. Study design This was a retrospective, descriptive review from clinical data in a tertiary care pediatric hospital in the US. Patients (n = 176) with idiopathic scoliosis with Cobb angles of $40 degrees who performed acceptable and repeatable preoperative pulmonary function testing were included. The primary outcome measure was the forced expiratory volume in the first second (FEV1)/forced vital capacity (FVC) ratio. Results The prevalence of OLD (low FEV1/FVC ratio) was 39% (68/176 patients). In multivariate modeling, radiographic measures were poor predictors of pulmonary function outcomes of FVC (r2 0.06), FEV1 (r2 0.05), FEV1/FVC ratio (r2 0.08), and total lung capacity (r2 0.06). Conclusions OLD is common in patients with idiopathic scoliosis. We recommend preoperative pulmonary function testing for patients with idiopathic scoliosis under consideration for spinal fusion surgery. (J Pediatr 2015;166:1018-21).
T
he prevalence of idiopathic scoliosis is estimated at 2%-3% in children.1 Complications of idiopathic scoliosis include back pain, poor body image, and impaired pulmonary function. Adolescents with idiopathic scoliosis and Cobb angles of 25-45 degrees are routinely managed with close observation, sometimes in conjunction with bracing to prevent spine curve progression.1 Adolescents with Cobb angles above 45-50 degrees are routinely managed with spinal fusion surgery.1 Progressive idiopathic scoliosis of this severity, requiring spinal fusion surgery, is associated with pulmonary function impairment.1 Among children with progressive idiopathic scoliosis, restrictive lung disease (RLD, defined as low lung volume) is common. In this population, decreases in lung capacity are associated with increases in the scoliosis Cobb angle.2 A 1995 study of 70 children with idiopathic scoliosis reported that 71% of patients had a forced vital capacity (FVC, defined as total air exhaled on spirometry) #80% predicted.3 Zhang et al studied 298 patients with scoliosis and reported that 61% of patients had an FVC .10. The parameter (b) estimates (with SEs and P values) for the predictors in the final models are reported, along with the proportion (r2) of variation explained by each model. Significance for all tests was set a priori at a < 0.05. All analyses were conducted using SAS 9.2 software (SAS Institute, Cary, North Carolina).
Results One hundred seventy-six patients with idiopathic scoliosis were included. Patient characteristics are shown in Table I. The study population was 86% female, reflecting the natural history of idiopathic scoliosis. The study group had normal mean values for FVC, FEV1, FEV1/FVC ratio, and TLC (Table I). However, there was marked heterogeneity within the group. One hundred seventy-six patients completed spirometry testing; 34% (68/176) had OLD on spirometry, defined as FEV1/FVC ratio below the 95% CI. Of the 68 patients with OLD, 52 had repeat spirometry testing after bronchodilator administration; 73% (38/52) continued to have an
Table I. Idiopathic scoliosis patient characteristics, overall, and by lung disease category RLDz
OLD† Continuous variables, mean ± SD (n)
All patients (176)
Yes (68)
No (108)
Yes (31)
No (144)
Height (cm) BMI-for-age z-score Age at scoliosis onset Cobb angle (degrees) Kyphosis angle (deg.) T-level count FVC% predicted FEV1% predicted FEV1/FVC FEF 25%-75% TLC% predicted FRC% predicted RV% predicted Categorical variable, % (n) Males Caucasian African American Other
161.7 8.8 0.3 1.1 13.2 2.1 55.2 11.7 27.6 14.4 8.0 1.9 100.9 15.8 92.2 16.1 81.1 7.4 77.4 23.7 (176) 94.9 13.5 86.7 17.2 77.0 27.9
162.2 9.1 0.1 1.0 13.1 2.2 55.9 12.9 28.2 14.4 8.2 2.0 100.6 17.8 84.0 14.9* 74.2 4.1* 56.4 14 (68)* 94.8 15.3 89.7 17.9 76.8 27.1
161.3 8.7 0.4 1.2 13.3 2.1 54.7 10.9 27.3 14.4 7.9 1.8 101.1 14.5 97.4 14.6 85.5 5.5 90.7 18.4 (108) 95.0 12.3 84.9 16.6 77.1 28.4
161.0 10.0 0.3 1.0* 12.7 2.2 57.7 10.9 21.9 16.6* 7.8 1.5 83.0 11.8* 75.8 12.5* 81.1 7.9 64.4 21.4 (31)* 76.6 6.4* 72.3 9.0* 60.9 27.6*
161.7 8.5 0.5 1.1 13.3 2.1 54.5 11.8 28.8 13.5 8.0 1.9 104.9 13.6 96.0 14.2 81.2 7.3 80.6 23.0 (144) 98.9 11.1 89.8 17.0 80.4 26.8
14% 84% 13% 3%
12% 84% 13% 3%
15% 84% 12% 4%
10% 94% 6% 0%
14% 82% 14% 4%
BMI, body mass index; RV, residual volume. T-level count is the number of thoracic vertebrae in the spine curve. % predicted is the percent of the mean predicted value based on standard reference equations.9,10 *P < .05 using 2-sample t test or c2 test – “yes” vs “no” for each lung disease category. †OLD was defined as a FEV1/FVC below the 95% CI. zRLD was defined as a TLC below the 95% CI.
1019
THE JOURNAL OF PEDIATRICS
www.jpeds.com
Vol. 166, No. 4
Table II. Pearson correlation results between radiographic measures and PFT variables Radiographic measures Cobb angle
Kyphosis angle
T-level count
PFT variables
r
P value
n
r
P value
n
r
P value
n
FVC% FEV1% FEV1/FVC FEF 25%-75% TLC% IC%
0.09573 0.13144 0.12821 0.17492 0.17242 0.07901
.2063 .0821 .0899 .0202 .0229 .3000
176 176 176 176 174 174
0.24794 0.18243 0.06964 0.07447 0.17549 0.05204
.0012 .0176 .3683 .3359 .0233 .5042
169 169 169 169 167 167
0.03696 0.11859 0.15839 0.16289 0.04274 0.04853
.6263 .1170 .0358 .0308 .5755 .5249
176 176 176 176 174 174
IC, inspiratory capacity. T-level count is the number of thoracic vertebrae in the spine curve. % is the percent of the mean predicted value based on standard reference equations.9,10
FEV1/FVC ratio below the 95% CI (consistent with fixed airway obstruction). Nineteen percent of these patients (10/52) with fixed OLD had moderate or severe OLD.6 One hundred seventy-five patients completed lung volume testing; 18% (31/175) with lung volume testing had RLD as defined by a TLC below the 95% CI. Ten percent of patients (3/31) with RLD had moderate or severe RLD.6 Seven percent of patients (12/175) who performed both spirometry and lung volume testing had a mixed ventilatory defect, with both OLD and RLD present. Eight of the 12 patients with a mixed ventilatory defect had moderate or severe lung disease.6 The PFT finding of a low FEV1/FVC ratio (OLD) and a low TLC (RLD) occurred independently. There was no statistical association between having a low FEV1/FVC ratio and a low TLC on c2 testing (P .96) or regression analysis (P .72). Fifty one percent of the study group (89/175) who performed both spirometry and lung volume testing had normal results, with an FEV1/FVC ratio and a TLC within the normal range. Pearson correlations between radiographic measures and PFT variables are shown in Table II. There was a positive correlation between the angle of kyphosis and FVC, FEV1, and TLC. There was an inverse correlation between the number of thoracic vertebrae in the spine curve and FEV1/ FVC and FEF 25%-75%. There was an inverse correlation between the Cobb angle and TLC and FEF 25%-75%. On multivariate regression (Table III), there remained a positive correlation between the angle of kyphosis and the FVC, FEV1, functional residual capacity (FRC), and TLC. On multivariate regression, there was an inverse correlation between the Cobb angle and the FEV1/FVC, TLC, and FRC, and the number of thoracic vertebrae in the curve was no longer a predictor of PFT outcomes. In the multivariate model, radiographic measures explained 5%-10% of the variance in pulmonary function outcomes (R2 data; Table III).
Discussion Lung function abnormalities are common in children with idiopathic scoliosis. Fifty percent of patients in our study had obstructive, restrictive, or mixed ventilatory defects. 1020
Twenty percent of patients had moderate to severe abnormalities based on ATS/ERS lung disease severity classifications.6 Higher Cobb angles were associated with lower FEV1/FVC, a lower FRC, and lower TLC values. Lower angles of kyphosis were associated with lower FVC, FEV1, and TLC and FRC values. However, over 90% of the variance in pulmonary function in our study was unexplained by angles of spine disease as measured on plain radiographs. Winter et al reported the association of hypokyphosis and pulmonary impairment.12 Newton et al reported higher rates of pulmonary impairment in association with higher Cobb angles and lower angles of kyphosis, consistent with our findings.2 These studies reported PFT outcomes of FVC, FEV1, and TLC, but did not report FEV1/FVC ratios, FEF 25%-75%, or on the prevalence of OLD.2,12 There were likely multiple mechanisms of OLD in our study population. Twenty-seven percent of patients with OLD who repeated PFT testing after a bronchodilator had reversible airway disease. Resolution of obstruction after bronchodilator was an indication that obstruction was caused by increased airway smooth muscle tone. Reversible airway disease is most commonly seen in asthma but can be seen in asymptomatic patients. The remaining 73% of patients with OLD who repeated PFT testing after a bronchodilator had airway obstruction that was not relieved by this
Table III. Multiple linear regression results of radiographic measures and PFT variables Potential regressors* PFT variables
Cobb angle (degrees), r, P value
FVC% 0.19 0.11, .07 FEV1% FEV1/FVC† 0.10 0.05, .044 TLC% 0.20 0.09, .024 FRC% 0.32 0.11, .004 RV% 0.28 0.18, .12
Kyphosis T-level angle (degrees), r, count, r, P value P value 0.28 0.08, .001 0.21 0.09, .014 0.17 0.07, .017 0.28 0.09, .002 -
-
R2 0.0615 0.0522 0.0798 0.0605 0.0975 0.0136
% is the percent of the mean predicted value based on standard reference equations.9,10 *Expressed as b SE(b), P-value. In cases with more than 1 regressor, R2 is the correlation coefficient adjusted for multiple explanatory variables. †Models were adjusted for height, age, and sex. Only height was a significant predictor (0.18 0.08, .027).
McPhail et al
ORIGINAL ARTICLES
April 2015 therapy, such as fixed airway obstruction can represent asthma variant, lower airway malacia, or intrathoracic airway compression.13,14 Our study was limited by its single-center, retrospective design. A multicenter study is needed to confirm the association of adolescent idiopathic scoliosis with OLD. It was beyond the scope of this study design to assess for mechanisms of disease. Further, we did not have specialized computer software needed to measure vertebral axial rotation. Although not a standard of clinical care, measures of vertebral axial rotation could have added to the robustness of our radiographic model. But despite those limitations, our study adds to the current literature, and the study reports an association of idiopathic scoliosis with OLD. Based on our results, we recommend preoperative PFT in children with idiopathic scoliosis. In patients with a low FEV1/FVC ratio, repeat testing should be performed after bronchodilator administration. If the FEV1/FVC ratio remains low, suggesting a fixed airway obstruction, assessment of the large airways via endoscopy, or chest imaging to assess for mechanisms of disease, should be considered.15-17 n
3.
4.
5. 6.
7. 8.
9. 10. 11.
12.
The authors thank Barbara Chini, MD, Robert Wood, MD, PhD, and Alvin Crawford, MD for their mentorship and assistance at the start of the project in helping shape the study design and conception. Submitted for publication Jan 20, 2014; last revision received Oct 20, 2014; accepted Dec 23, 2014. Reprint requests: Gary L. McPhail, MD, Division of Pulmonary Medicine, Cincinnati Children’s Hospital Medical Center, ML 2021, 3333 Burnet Ave, Cincinnati, OH 45229-3039. E-mail: [email protected]
References 1. Rose PS, Lenke LG. Classification of operative adolescent idiopathic scoliosis: treatment guidelines. Orthop Clin North Am 2007;38:521-9. 2. Newton PO, Faro FD, Gollogly S, Betz RR, Lenke LG, Lowe TG. Results of preoperative pulmonary function testing of adolescents with idio-
Obstructive Lung Disease in Children with Idiopathic Scoliosis
13.
14.
15. 16.
17.
pathic scoliosis. A study of six hundred and thirty-one patients. J Bone Joint Surg Am 2005;87:1937-46. Upadhyay SS, Mullaji AB, Luk KD, Leong JC. Relation of spinal and thoracic cage deformities and their flexibilities with altered pulmonary functions in adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 1995;20:2415-20. Zhang JG, Wang W, Qiu GX, Wang YP, Weng XS, Xu HG. The role of preoperative pulmonary function tests in the surgical treatment of scoliosis. Spine (Phila Pa 1976) 2005;30:218-21. Boyer J, Amin N, Taddonio R, Dozor AJ. Evidence of airway obstruction in children with idiopathic scoliosis. Chest 1996;109:1532-5. Pellegrino R, Viegi G, Brusasco V, Crapo RO, Burgos F, Casaburi R, et al. Interpretative strategies for lung function tests. Eur Respir J 2005;26:948-68. Miller MR, Hankinson J, Brusasco V, Burgos F, Casaburi R, Coates A, et al. Standardisation of spirometry. Eur Respir J 2005;26:319-38. Wanger J, Clausen JL, Coates A, Pedersen OF, Brusasco V, Burgos F, et al. Standardisation of the measurement of lung volumes. Eur Respir J 2005;26:511-22. Wang X, Dockery DW, Wypij D, Fay ME, Ferris BG Jr. Pulmonary function between 6 and 18 years of age. Pediatr Pulmonol 1993;15:75-88. Zapletal A, Samanek M, Paul T. Lung function in children and adolescents. Prog Respir Res 1987;22:118. Hepper NG, Black LF, Fowler WS. Relationship of lung volume to height and arm span in normal subjects and in patients with spinal deformity. Am Rev Respir Dis 1965;91:356-62. Winter RB, Lovell WW, Moe JH. Excessive thoracic lordosis and loss of pulmonary function in patients with idiopathic scoliosis. J Bone Joint Surg Am 1975;57:972-7. Fabbri LM, Romagnoli M, Corbetta L, Casoni G, Busljetic K, Turato G. Differences in airway inflammation in patients with fixed airflow obstruction due to asthma or chronic obstructive pulmonary disease. Am J Respir Crit Care Med 2003;167:418-24. Jang AS, Park JS, Lee JH, Park SW, Kim DJ, Uh ST. Asthmatics without rhinitis have more fixed airway obstruction than those with concurrent rhinitis. Allergy Asthma Immunol Res 2010;2:108-13. Donnelly LF, Bisset GS III. Airway compression in children with abnormal thoracic configuration. Radiology 1998;206:323-6. de Torres Garcıa I, de Cabo Moreno P, Ramırez AM. Extrinsic bronchial obstruction caused by scoliosis. Spine (Phila Pa 1976) 2013;38: E840-3. Goussard P, Gie R, Andronikou S, Fourie PR. A correctable cause of lung collapse in an adolescent with severe scoliosis causing compression of the bronchial tree. BMJ Case Rep 2013;2013.
1021
T
he prevalence of idiopathic scoliosis is estimated at 2%-3% in children.1 Complications of idiopathic scoliosis include back pain, poor body image, and impaired pulmonary function. Adolescents with idiopathic scoliosis and Cobb angles of 25-45 degrees are routinely managed with close observation, sometimes in conjunction with bracing to prevent spine curve progression.1 Adolescents with Cobb angles above 45-50 degrees are routinely managed with spinal fusion surgery.1 Progressive idiopathic scoliosis of this severity, requiring spinal fusion surgery, is associated with pulmonary function impairment.1 Among children with progressive idiopathic scoliosis, restrictive lung disease (RLD, defined as low lung volume) is common. In this population, decreases in lung capacity are associated with increases in the scoliosis Cobb angle.2 A 1995 study of 70 children with idiopathic scoliosis reported that 71% of patients had a forced vital capacity (FVC, defined as total air exhaled on spirometry) #80% predicted.3 Zhang et al studied 298 patients with scoliosis and reported that 61% of patients had an FVC .10. The parameter (b) estimates (with SEs and P values) for the predictors in the final models are reported, along with the proportion (r2) of variation explained by each model. Significance for all tests was set a priori at a < 0.05. All analyses were conducted using SAS 9.2 software (SAS Institute, Cary, North Carolina).
Results One hundred seventy-six patients with idiopathic scoliosis were included. Patient characteristics are shown in Table I. The study population was 86% female, reflecting the natural history of idiopathic scoliosis. The study group had normal mean values for FVC, FEV1, FEV1/FVC ratio, and TLC (Table I). However, there was marked heterogeneity within the group. One hundred seventy-six patients completed spirometry testing; 34% (68/176) had OLD on spirometry, defined as FEV1/FVC ratio below the 95% CI. Of the 68 patients with OLD, 52 had repeat spirometry testing after bronchodilator administration; 73% (38/52) continued to have an
Table I. Idiopathic scoliosis patient characteristics, overall, and by lung disease category RLDz
OLD† Continuous variables, mean ± SD (n)
All patients (176)
Yes (68)
No (108)
Yes (31)
No (144)
Height (cm) BMI-for-age z-score Age at scoliosis onset Cobb angle (degrees) Kyphosis angle (deg.) T-level count FVC% predicted FEV1% predicted FEV1/FVC FEF 25%-75% TLC% predicted FRC% predicted RV% predicted Categorical variable, % (n) Males Caucasian African American Other
161.7 8.8 0.3 1.1 13.2 2.1 55.2 11.7 27.6 14.4 8.0 1.9 100.9 15.8 92.2 16.1 81.1 7.4 77.4 23.7 (176) 94.9 13.5 86.7 17.2 77.0 27.9
162.2 9.1 0.1 1.0 13.1 2.2 55.9 12.9 28.2 14.4 8.2 2.0 100.6 17.8 84.0 14.9* 74.2 4.1* 56.4 14 (68)* 94.8 15.3 89.7 17.9 76.8 27.1
161.3 8.7 0.4 1.2 13.3 2.1 54.7 10.9 27.3 14.4 7.9 1.8 101.1 14.5 97.4 14.6 85.5 5.5 90.7 18.4 (108) 95.0 12.3 84.9 16.6 77.1 28.4
161.0 10.0 0.3 1.0* 12.7 2.2 57.7 10.9 21.9 16.6* 7.8 1.5 83.0 11.8* 75.8 12.5* 81.1 7.9 64.4 21.4 (31)* 76.6 6.4* 72.3 9.0* 60.9 27.6*
161.7 8.5 0.5 1.1 13.3 2.1 54.5 11.8 28.8 13.5 8.0 1.9 104.9 13.6 96.0 14.2 81.2 7.3 80.6 23.0 (144) 98.9 11.1 89.8 17.0 80.4 26.8
14% 84% 13% 3%
12% 84% 13% 3%
15% 84% 12% 4%
10% 94% 6% 0%
14% 82% 14% 4%
BMI, body mass index; RV, residual volume. T-level count is the number of thoracic vertebrae in the spine curve. % predicted is the percent of the mean predicted value based on standard reference equations.9,10 *P < .05 using 2-sample t test or c2 test – “yes” vs “no” for each lung disease category. †OLD was defined as a FEV1/FVC below the 95% CI. zRLD was defined as a TLC below the 95% CI.
1019
THE JOURNAL OF PEDIATRICS
www.jpeds.com
Vol. 166, No. 4
Table II. Pearson correlation results between radiographic measures and PFT variables Radiographic measures Cobb angle
Kyphosis angle
T-level count
PFT variables
r
P value
n
r
P value
n
r
P value
n
FVC% FEV1% FEV1/FVC FEF 25%-75% TLC% IC%
0.09573 0.13144 0.12821 0.17492 0.17242 0.07901
.2063 .0821 .0899 .0202 .0229 .3000
176 176 176 176 174 174
0.24794 0.18243 0.06964 0.07447 0.17549 0.05204
.0012 .0176 .3683 .3359 .0233 .5042
169 169 169 169 167 167
0.03696 0.11859 0.15839 0.16289 0.04274 0.04853
.6263 .1170 .0358 .0308 .5755 .5249
176 176 176 176 174 174
IC, inspiratory capacity. T-level count is the number of thoracic vertebrae in the spine curve. % is the percent of the mean predicted value based on standard reference equations.9,10
FEV1/FVC ratio below the 95% CI (consistent with fixed airway obstruction). Nineteen percent of these patients (10/52) with fixed OLD had moderate or severe OLD.6 One hundred seventy-five patients completed lung volume testing; 18% (31/175) with lung volume testing had RLD as defined by a TLC below the 95% CI. Ten percent of patients (3/31) with RLD had moderate or severe RLD.6 Seven percent of patients (12/175) who performed both spirometry and lung volume testing had a mixed ventilatory defect, with both OLD and RLD present. Eight of the 12 patients with a mixed ventilatory defect had moderate or severe lung disease.6 The PFT finding of a low FEV1/FVC ratio (OLD) and a low TLC (RLD) occurred independently. There was no statistical association between having a low FEV1/FVC ratio and a low TLC on c2 testing (P .96) or regression analysis (P .72). Fifty one percent of the study group (89/175) who performed both spirometry and lung volume testing had normal results, with an FEV1/FVC ratio and a TLC within the normal range. Pearson correlations between radiographic measures and PFT variables are shown in Table II. There was a positive correlation between the angle of kyphosis and FVC, FEV1, and TLC. There was an inverse correlation between the number of thoracic vertebrae in the spine curve and FEV1/ FVC and FEF 25%-75%. There was an inverse correlation between the Cobb angle and TLC and FEF 25%-75%. On multivariate regression (Table III), there remained a positive correlation between the angle of kyphosis and the FVC, FEV1, functional residual capacity (FRC), and TLC. On multivariate regression, there was an inverse correlation between the Cobb angle and the FEV1/FVC, TLC, and FRC, and the number of thoracic vertebrae in the curve was no longer a predictor of PFT outcomes. In the multivariate model, radiographic measures explained 5%-10% of the variance in pulmonary function outcomes (R2 data; Table III).
Discussion Lung function abnormalities are common in children with idiopathic scoliosis. Fifty percent of patients in our study had obstructive, restrictive, or mixed ventilatory defects. 1020
Twenty percent of patients had moderate to severe abnormalities based on ATS/ERS lung disease severity classifications.6 Higher Cobb angles were associated with lower FEV1/FVC, a lower FRC, and lower TLC values. Lower angles of kyphosis were associated with lower FVC, FEV1, and TLC and FRC values. However, over 90% of the variance in pulmonary function in our study was unexplained by angles of spine disease as measured on plain radiographs. Winter et al reported the association of hypokyphosis and pulmonary impairment.12 Newton et al reported higher rates of pulmonary impairment in association with higher Cobb angles and lower angles of kyphosis, consistent with our findings.2 These studies reported PFT outcomes of FVC, FEV1, and TLC, but did not report FEV1/FVC ratios, FEF 25%-75%, or on the prevalence of OLD.2,12 There were likely multiple mechanisms of OLD in our study population. Twenty-seven percent of patients with OLD who repeated PFT testing after a bronchodilator had reversible airway disease. Resolution of obstruction after bronchodilator was an indication that obstruction was caused by increased airway smooth muscle tone. Reversible airway disease is most commonly seen in asthma but can be seen in asymptomatic patients. The remaining 73% of patients with OLD who repeated PFT testing after a bronchodilator had airway obstruction that was not relieved by this
Table III. Multiple linear regression results of radiographic measures and PFT variables Potential regressors* PFT variables
Cobb angle (degrees), r, P value
FVC% 0.19 0.11, .07 FEV1% FEV1/FVC† 0.10 0.05, .044 TLC% 0.20 0.09, .024 FRC% 0.32 0.11, .004 RV% 0.28 0.18, .12
Kyphosis T-level angle (degrees), r, count, r, P value P value 0.28 0.08, .001 0.21 0.09, .014 0.17 0.07, .017 0.28 0.09, .002 -
-
R2 0.0615 0.0522 0.0798 0.0605 0.0975 0.0136
% is the percent of the mean predicted value based on standard reference equations.9,10 *Expressed as b SE(b), P-value. In cases with more than 1 regressor, R2 is the correlation coefficient adjusted for multiple explanatory variables. †Models were adjusted for height, age, and sex. Only height was a significant predictor (0.18 0.08, .027).
McPhail et al
ORIGINAL ARTICLES
April 2015 therapy, such as fixed airway obstruction can represent asthma variant, lower airway malacia, or intrathoracic airway compression.13,14 Our study was limited by its single-center, retrospective design. A multicenter study is needed to confirm the association of adolescent idiopathic scoliosis with OLD. It was beyond the scope of this study design to assess for mechanisms of disease. Further, we did not have specialized computer software needed to measure vertebral axial rotation. Although not a standard of clinical care, measures of vertebral axial rotation could have added to the robustness of our radiographic model. But despite those limitations, our study adds to the current literature, and the study reports an association of idiopathic scoliosis with OLD. Based on our results, we recommend preoperative PFT in children with idiopathic scoliosis. In patients with a low FEV1/FVC ratio, repeat testing should be performed after bronchodilator administration. If the FEV1/FVC ratio remains low, suggesting a fixed airway obstruction, assessment of the large airways via endoscopy, or chest imaging to assess for mechanisms of disease, should be considered.15-17 n
3.
4.
5. 6.
7. 8.
9. 10. 11.
12.
The authors thank Barbara Chini, MD, Robert Wood, MD, PhD, and Alvin Crawford, MD for their mentorship and assistance at the start of the project in helping shape the study design and conception. Submitted for publication Jan 20, 2014; last revision received Oct 20, 2014; accepted Dec 23, 2014. Reprint requests: Gary L. McPhail, MD, Division of Pulmonary Medicine, Cincinnati Children’s Hospital Medical Center, ML 2021, 3333 Burnet Ave, Cincinnati, OH 45229-3039. E-mail: [email protected]
References 1. Rose PS, Lenke LG. Classification of operative adolescent idiopathic scoliosis: treatment guidelines. Orthop Clin North Am 2007;38:521-9. 2. Newton PO, Faro FD, Gollogly S, Betz RR, Lenke LG, Lowe TG. Results of preoperative pulmonary function testing of adolescents with idio-
Obstructive Lung Disease in Children with Idiopathic Scoliosis
13.
14.
15. 16.
17.
pathic scoliosis. A study of six hundred and thirty-one patients. J Bone Joint Surg Am 2005;87:1937-46. Upadhyay SS, Mullaji AB, Luk KD, Leong JC. Relation of spinal and thoracic cage deformities and their flexibilities with altered pulmonary functions in adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 1995;20:2415-20. Zhang JG, Wang W, Qiu GX, Wang YP, Weng XS, Xu HG. The role of preoperative pulmonary function tests in the surgical treatment of scoliosis. Spine (Phila Pa 1976) 2005;30:218-21. Boyer J, Amin N, Taddonio R, Dozor AJ. Evidence of airway obstruction in children with idiopathic scoliosis. Chest 1996;109:1532-5. Pellegrino R, Viegi G, Brusasco V, Crapo RO, Burgos F, Casaburi R, et al. Interpretative strategies for lung function tests. Eur Respir J 2005;26:948-68. Miller MR, Hankinson J, Brusasco V, Burgos F, Casaburi R, Coates A, et al. Standardisation of spirometry. Eur Respir J 2005;26:319-38. Wanger J, Clausen JL, Coates A, Pedersen OF, Brusasco V, Burgos F, et al. Standardisation of the measurement of lung volumes. Eur Respir J 2005;26:511-22. Wang X, Dockery DW, Wypij D, Fay ME, Ferris BG Jr. Pulmonary function between 6 and 18 years of age. Pediatr Pulmonol 1993;15:75-88. Zapletal A, Samanek M, Paul T. Lung function in children and adolescents. Prog Respir Res 1987;22:118. Hepper NG, Black LF, Fowler WS. Relationship of lung volume to height and arm span in normal subjects and in patients with spinal deformity. Am Rev Respir Dis 1965;91:356-62. Winter RB, Lovell WW, Moe JH. Excessive thoracic lordosis and loss of pulmonary function in patients with idiopathic scoliosis. J Bone Joint Surg Am 1975;57:972-7. Fabbri LM, Romagnoli M, Corbetta L, Casoni G, Busljetic K, Turato G. Differences in airway inflammation in patients with fixed airflow obstruction due to asthma or chronic obstructive pulmonary disease. Am J Respir Crit Care Med 2003;167:418-24. Jang AS, Park JS, Lee JH, Park SW, Kim DJ, Uh ST. Asthmatics without rhinitis have more fixed airway obstruction than those with concurrent rhinitis. Allergy Asthma Immunol Res 2010;2:108-13. Donnelly LF, Bisset GS III. Airway compression in children with abnormal thoracic configuration. Radiology 1998;206:323-6. de Torres Garcıa I, de Cabo Moreno P, Ramırez AM. Extrinsic bronchial obstruction caused by scoliosis. Spine (Phila Pa 1976) 2013;38: E840-3. Goussard P, Gie R, Andronikou S, Fourie PR. A correctable cause of lung collapse in an adolescent with severe scoliosis causing compression of the bronchial tree. BMJ Case Rep 2013;2013.
1021
