Eur Spine J DOI 10.1007/s00586-014-3425-5
ORIGINAL ARTICLE
Has overweight any influence on the effectiveness of conservative treatment in patients with low back pain? Dorothea Daentzer • Tina Hohls • Christine Noll
Received: 18 April 2014 / Revised: 12 June 2014 / Accepted: 13 June 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract Purpose Low back pain and overweight are two relevant disabling health conditions. To date, there is a lack of information about the effectiveness of nonoperative therapy in persons with overweight and low back pain. The aim of our study was to evaluate if overweight has any influence on the effectivity of conservative treatment in patients with low back pain during a mid- to long-term time period. Methods 128 patients with low back pain participated in this study. All of them got an inpatient conservative treatment program. The weight status was classified according to the body mass index (BMI) in three weight groups (normal, overweight, obesity). The patients were asked to fill out a standardized questionnaire regarding self-reported pain with the visual analog scale and their disability with the Oswestry Disability Index and the Roland-Morris Disability Questionnaire at four time points (beginning and end of hospital stay and after 5 and 17 months). Results Concerning the short-term results of the three scores, we always observed an improvement of the patients’ condition with statistically significant reduction of pain and disability at discharge. This was true for the total collective as well as for each of the three BMI-groups when considered separately. The pain intensity and disability
D. Daentzer (&) C. Noll Spine Section, Orthopedic Department of Hannover Medical School, Diakoniekrankenhaus Annastift gGmbH, Anna-vonBorries-Str. 1-7, 30625 Hannover, Germany e-mail: [email protected] T. Hohls Clinic for Anesthesiology, Intensive Care and Pain Therapy, Klinikum Nordstadt, Klinikum Region Hannover, Hannover, Germany
were still and mostly statistically significantly decreased in the mid- to long-term follow-up. Regarding the three BMIgroups among themselves, the differences of the data in the pain and disability scores showed generally no statistical significance. Conclusions We conclude for the first time that a conservative treatment program in patients even with chronic low back pain is effective both in a short-term and a midto long-term time period respectively without any significant differences between patients with a normal BMI or with overweight or obesity. Keywords BMI Body mass index Conservative treatment Low back pain Obesity Overweight
Introduction Low back pain is a relevant medical problem affecting 70–85 % of the population at least once during their lifetime [1–5]. Obesity is a prevalent condition and characterized by excess adipose tissue contributing to metabolic dysfunction [6–8]. It has been suggested that obesity may affect pain and disability levels in chronic low back pain and can increase the risk of future chronic low back pain development [9, 10]. Several studies have shown a positive correlation between low back pain and overweight [9, 11– 15]. These findings were supported by the fact that most patients have noticed reduction in low back pain after weight loss, either with a diet or after bariatric surgical procedures [6, 16, 17]. Some authors further showed that people with overweight demonstrate more signs of disc degeneration as a possible cause of low back pain than persons with normal weight [18–20]. In contrast, a systematic literature review found only in 32 % of the studies
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Eur Spine J Table 1 Main diagnosis of the 128 patients (more than one diagnosis could be mentioned because of the possibility of combined pathologies, for example spondylolisthesis plus spinal canal stenosis) Diagnosis
n
%
Degenerative disc disease
78
60.9
Disc protrusion or prolapse
47
36.7
Spondylolisthesis (degenerative or lytic) Spinal canal stenosis
27 27
21.1 21.1
Facet joint arthrosis
27
21.1
Degenerative scoliosis
16
12.5
(21 of 65) a positive association between the body mass index (BMI) or body weight and low back pain [21]. The therapy of choice for patients with low back pain is conservative treatment and mainly exercise except for conditions when surgery is mandatory like in tumorous, traumatic or inflammatory situations [22, 23]. One study even showed a positive effect on chronic low back pain in obese persons who performed exercises for one or more hours per week in contrast to those who were inactive [24]. However, the exact influence of the body weight on patients with low back pain who had a conservative treatment program is already not really known. Only one recently published study investigated the relationship between the BMI and changes in pain and disability resulting from exercise-based chronic low back pain therapy in which the authors found no correlation [25]. But the follow-up in this trial was only 8 weeks, so we do not have any mid- to long-term data to date. Therefore, the aim of our study was to evaluate if overweight has any influence on the effectiveness of conservative treatment in patients with low back pain and to analyze the results during a follow-up period up to 17 months.
Patients and methods 128 patients participated in this study. All of them suffered from low back pain and had a stay as an inpatient. The local Ethical Committee (Hannover Medical School, Hannover, Germany) gave its approval to this retrospective study and to analyze the data which had been routinely collected in all low back pain patients in our clinic. Indication for treatment in the hospital was therapy resistant complaints after conservative therapy under outpatient conditions or exacerbated pain causing immobilization. Inclusion criteria were only degenerative changes of the lumbar spine as well as lytic spondylolisthesis. The main diagnosis was classified according to conventional X-rays, computer tomography or magnetic resonance imaging and
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listed in Table 1. Patients with back pain due to tumorous, inflammatory or traumatic origin had been excluded, as well as persons with urgent reasons for operation such as paresis or intractable pain. Measures All patients had measurements of their body height and weight to calculate the body mass index (BMI, kg/m2) [8]. According to the BMI persons were classified into three groups [8]: Group 1 with BMI \25.0 kg/m2 (normal weight). Group 2 with BMI 25–29.9 kg/m2 (overweight). Group 3 with BMI [29.9 kg/m2 (obesity). The questionnaire included self-reported information regarding the duration of back and leg pain and also data to classify the pain intensity which was determined with the visual analog scale (VAS) as a measuring instrument for the subjective level of pain pointed out in a continuous line between two end points representing no pain ‘‘0’’ (left anchor) and maximal imaginable pain ‘‘10’’ (right anchor) [26, 27]. The self-reported functional impairment was analyzed on the one hand with the Oswestry Disability Index (ODI) as a 10-item questionnaire resulting in a score out of 50 converted to percentage [23, 26–28]. The disability scores of the ODI can be interpreted in the following five grades: 0–20 %: minimal disability. 20–40 %: moderate disability. 40–60 %: severe disability. 60–80 %: crippled. 80–100 %: bed-bound. On the other hand, the Roland-Morris Disability Questionnaire (RM) was used which is a 24-item questionnaire also converted to percentage [29]. The higher the score, the higher is the disability (for example 0 % means no disability, 100 % means severe disability). The VAS, ODI and RM are valid and reliable methods of measuring pain and disability [27, 30]. The participants were instructed to fill out the same questionnaire at four points of time: 1. 2. 3. 4.
At the beginning of hospital stay. At the end of hospital stay (discharge). After a mean follow-up at 5 months. After a mean follow-up at 17 months.
If the patients had not sent back the questionnaires spontaneously after 5 or 17 months, they were remembered by letter or by phone, so that as much as possible forms could be collected until the end of the study duration. Nevertheless, a certain drop out rate had to be noted. A few
Eur Spine J
patients stopped their participation because of a lack of compliance and some persons had conversion of the conservative treatment to surgery. Treatment All patients had a standardized conservative treatment program. It consisted of physiotherapy and manual therapy, which was performed daily. Physical procedures as local heat, massage, electrotherapy, and medical bathing were alternatively applied every 2 days. The patients had also daily back therapy training. Medication was individually adapted to the patient’s complaints and pain intensity and consisted of analgesics according to the scheme of the World Health Organization and co-analgesics as muscle relaxants and antidepressants. Furthermore, the patients got local injections in the form of facet joint injections or periradicular therapy based on the underlying pathology. At the time of discharge, the patients were advised to continue the conservative treatment in an outpatient setup. Statistical analyses Statistical analyses were performed using SPSSÒ for Windows (version 14.0, SPSS Inc., Chicago, IL, USA). All analyses were conducted for the total patient collective and for the three BMI-groups separately. Differences in the outcome parameters within the study period at the four time points as well between the three BMI-groups were studied by using the t test. A p value of \0.05 was considered significant.
Results
(72.7 %) at time 3 and 88 (68.8 %) at time 4. All data which were complete to the different moments were included into statistical analysis. Regarding the drop outs there were no statistical significant differences between the three BMI-groups. Many of the patients had chronic complaints with a mean duration of low back pain of 113 months (range 3 weeks to 540 months) and leg pain of 34 months (range 2 weeks to 360 months). The average length of the hospital stay was 9.4 days (range 2–46 days). Outcome data (scores) The results regarding the VAS at the four time points are presented in Fig. 1 for the total study collective and in Table 2 for the three BMI-groups in direct comparison. In the total patient group (Fig. 1), the pain intensity was statistically significantly decreased between time 1 and time 2 (p \ 0.001), time 1 and time 3 (p \ 0.001) and time 1 and time 3 (p \ 0.001). However, the data then showed statistically significant increase between time 2 and time 3 (p \ 0.001) and between time 2 and time 4 (p = 0.004). Concerning the results among the three BMI-groups (Table 2), we did not found any statistically significant differences at each of the four moments. Analogous to this, Fig. 2 and also Table 2 demonstrate the data of the ODI and Fig. 3 and Table 2 the findings of the RM. Regarding the data of the ODI (Fig. 2), we observed statistically significant improvement between time 1 and each of the time points during follow-up (time 1 to time 2 with p \ 0.001, time 1 to time 3 with p = 0.001 and time 1 to time 4 with p \ 0.001). In a similar way, improvement in the RM was seen between the initial time point and time 2 (p \ 0.001) and time 1 to time 3 (p = 0.031) (Fig. 3). Analogous to the findings of the VAS, there were no
Patient characteristics The mean age of the 75 women (58.9 %) and 53 men (41.1 %) was 60.9 years (range 25–88 years). 45 patients (35.2 %) had a normal body weight with a BMI \25.0 kg/ m2 (BMI-group 1). 47 persons (36.7 %) were classified as overweight with a BMI between 25.0 and 29.9 kg/m2 (BMI-group 2). 36 patients (28.1 %) had a BMI [29.9 kg/ m2 and belonged to the obese collective (BMI-group 3). The average BMI of the total study group was 27.5 kg/m2. The data of 40 participants could not be included into the final analysis. 29 of the 128 patients (22.7 %) had a surgical procedure during the follow-up because of therapy resistant symptoms. 11 (8.6 %) persons either had not sent back the questionnaire or had stopped their attendance for any reason. The number of people of whom the data were complete to the four different time points was the following: 128 (100 %) at time 1, 111 (86.7 %) at time 2, 93
Fig. 1 Mean VAS during the follow-up at the four time points in the total study collective. Asterisks means statistically significant differences between two columns connected with a bar
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Eur Spine J Table 2 Mean VAS, ODI (%) and RM (%) and standard deviation during the follow-up at the four time points for the 3 BMI-groups in direct comparison BMIgroup
Time 1
Time 2
Time 3
Time 4
VAS 1
6.8 ± 2.4
3.9 ± 2.8
4.5 ± 2.7
4.3 ± 3.1
2
7.6 ± 2.0
3.9 ± 3.0
5.8 ± 2.8
5.5 ± 2.9
3
7.3 ± 2.0
4.4 ± 2.6
6.2 ± 2.5
6.0 ± 2.2
47.0 ± 19.7
35.2 ± 21.2
36.1 ± 21.7
32.4 ± 20.9
ODI (%) 1 2
49.6 ± 17.6
39.9 ± 20.8
43.0 ± 17.8
37.8 ± 19.3
3
53.0 ± 13.2
44.0 ± 13.3
46.6 ± 15.9
40.9 ± 17.7
1
56.7 ± 23.4
43.3 ± 25.5
48.7 ± 26.9
51.4 ± 26.0
2
55.7 ± 18.7
45.0 ± 22.9
51.6 ± 19.5
49.3 ± 22.5
3
58.3 ± 14.9
48.3 ± 18.9
51.0 ± 18.3
53.3 ± 21.6
RM (%)
Fig. 2 Mean ODI (%) during the follow-up at the four time points in the total study collective. Asterisks means statistically significant differences between two columns connected with a bar
Fig. 3 Mean RM (%) during the follow-up at the four time points in the total study collective. Asterisks means statistically significant differences between two columns connected with a bar
intensity again was significantly reduced between time 1 and time 2 (p = 0.000), but significantly increased between time 2 and time 3 (p = 0.001). Similarly, the data of the ODI are shown in the Fig. 5a– c. Analogous to the VAS, we saw statistically significant decrease both in BMI-group 1 and BMI-group 2 between time 1 and time 2 (each with p = 0.000) and between time 1 and time 4 (BMI-group 1 with p = 0.033, BMI-group 2 with p = 0.001) (Fig. 5a, b). Additionally, the BMI-group 3 had significant improvement between time 1 and time 2 (p = 0.000) and time 1 and time 4 (p = 0.005) (Fig. 5c). The data of the RM are also presented in the Fig. 5a–c. In all three BMI-groups, the disability was statistically significantly reduced only between time 1 and time 2 (BMI-group 1 with p = 0.013, BMI-group 2 with p = 0.000 and BMI-group 3 with p = 0.001).
Discussion statistically significant differences in the ODI and the RM during the follow-up between the three BMI-groups (Table 2). In the Fig. 4a–c the data of the VAS during the followup are presented individually according to the three BMIgroups to point out any statistically significant differences within the same weight category. In the BMI-group 1 (Fig. 4a), we observed a statistically significant decrease of pain intensity between time 1 and time 2 (p = 0.000) and between time 1 and time 4 (p = 0.016). This was the same for BMI-group 2 (time 1 to time 2 with p = 0.000, time 1 to time 4 with p = 0.000) (Fig. 4b). However, pain increase was significant between time 2 and time 3 (p = 0.019). In the BMI-group 3 (Fig. 4c) the pain
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This is the first study to investigate the effectiveness of an inpatient conservative treatment program in patients with low back pain with special interest to the relationship between BMI and therapy-induced changes in self-reported pain and disability. With a distribution of only about onethird (35.2 %) of persons with normal weight and approximately two-thirds (64.8 %) of overweight or obese individuals, the clinical relevance of supernutrition in our probably representative study collective becomes obvious. Concerning the short-term results of the data of the three scores (VAS, ODI and RM), we always observed an improvement of the patients’ condition with statistically significant reduction of the pain and disability at discharge. This was true for the total collective as well as for each of
Eur Spine J
Fig. 4 Mean VAS during the follow-up at the four time points individually considered according to the three BMI-groups. a BMIgroup 1, b BMI-group 2, c BMI-group 3. Asterisks means statistically significant differences between two columns connected with a bar
Fig. 5 Mean ODI (%) and RM (%) during the follow-up at the four time points individually considered according to the three BMIgroups. a BMI-group 1, b BMI-group 2, c BMI-group 3. Asterisks means statistically significant differences between two columns connected with a bar
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Eur Spine J
the three BMI-groups when considered separately. This finding is a clear demonstration of the effectiveness of the stationary conservative treatment intervention even in patients with chronic low back pain and independent of the body weight. Furthermore, the pain intensity and the disability were still and mostly statistically significantly decreased in the mid- to long-term follow-up. It can be concluded, that there is a certain long lasting positive effect of this conservative therapy program. However, it cannot be estimated if this course is only a result of the inpatient treatment or alternatively a consequence of continued exercises in an outpatient basis or a combination of both, because this topic was not the scope of this study. Regarding the three BMI-groups among themselves, the data of the pain and disability scores were generally not statistically significantly different. It means that the condition of all persons was absolutely comparable independent of their body weight to each time point during the follow-up. However, we can state that in most of all data the normal weighted persons (BMI-group 1) showed the lowest pain intensity and disability, and the obese patients (BMI-group 3) demonstrated the highest complaints and functional impairment. In a recently published manuscript which is the only one dealing with a similar problem the relationship between BMI and exercise-induced changes in selfreported pain and disability in patients with chronic low back pain was investigated [25]. The authors had also included 128 persons of whom 77 % were classified as overweight and obese. Clinically meaningful reductions (C30 %) in VAS and ODI after exercise were experienced by 57.8 and 46.9 % of patients, respectively [31]. Their results were similar to our findings with no evidence of a baseline relationship between BMI and pain or disability and no relationship between baseline BMI and changes in pain and disability after exercise. In spite of the excellent comparability of the quintessence between both studies, there are some relevant differences to our evaluation. The longest follow-up in the presented patient group was 17 months in contrast to only 8 weeks in the investigation of Brooks et al. [25] which is a relative short observation period. The initial self-reported pain and disability were clearly higher in our collective with an average VAS of 7.2 and ODI of 49.9 % (meaning severe disability) compared to the patients of Brooks et al. with an average VAS of 3.95 and ODI of 23.65 % (representing moderate disability). The authors consequently conclude that their results should not be generalized or transferred to persons with higher pain or disability levels. Nevertheless, the statements of both studies are the same. First, a conservative treatment intervention in patients with chronic low back pain is effective both in a short-term and a mid- to long-term follow-up period. Second, there is no
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relationship between the BMI and the pain intensity and disability meaning that we can expect a positive effect in patients both with normal weight and even in overweight or obese persons in a similar way.
Limitations of the study One limitation is the fact that we had a drop out rate of 31.2 % until the end of the study which was mainly because of converting to operation in 22.7 % of the patients in case of therapy resistant complaints. Otherwise, we could include all of the patients’ data into statistical analysis until data acquisition had to be stopped. Another criticism is the lack of information about the kind of therapy after discharge. We could not present any data if the patients had continued their conservative treatment, in which intensity they performed their therapy or if they had stopped their intervention program at any time, because this was not the main topic of our study.
Conclusion According to our data we can conclude for the very first time that a conservative treatment program in patients even with chronic low back pain is effective both in a short-term and a mid- to long-term time period without any significant differences between patients with a normal BMI or with overweight or obesity, respectively. Therefore, we should strongly recommend conservative therapy in these persons independent on their body weight. Further research is necessary to get more information about the influence of a relevant weight loss on the pain intensity and disability during conservative therapy in patients with low back pain. Acknowledgments We want to thank Dr. Ludwig Hoy from the Institute for Biometry, Hannover Medical School, Germany, for his excellent support in performing the statistical analyses. Conflict of interest interest.
None of the authors has any potential conflict of
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19. Liuke M, Solovieva S, Lamminen A, Luoma K, Leino-Arjas P, Luukkonen R, Riihima¨ki H (2005) Disc degeneration of the lumbar spine in relation to overweight. Int J Obes 29:903–908 20. Shiri R, Karppinen J, Leino-Arjas P, Solovieva S, Varonen H, Kalso E, Ukkola O, Viikari-Junura E (2007) Cardiovascular and lifestyle risk factors in lumbar radicular pain or clinically defined sciatica: a systematic review. Eur Spine J 16:2043–2054 21. Leboeuf-Yde C (2000) Body weight and low back pain. A systematic literature review of 56 journal articles reporting on 65 epidemiologic studies. Spine 25:226–237 22. Koumantakis GA, Watson PJ, Oldham JA (2005) Supplementation of general endurance exercise only. Physiological and functional outcomes of a randomised controlled trial of patients with recurrent low back pain. Clin Biomech 20:474–482 23. Marshall PW, Murphy BA (2008) Muscle activation changes after exercise rehabilitation for chronic low back pain. Arch Phys Med Rehabil 89:1305–1313 24. Nilsen TI, Holtermann A, Mork PJ (2011) Physical exercise, body mass index, and risk of chronic pain in the low back and neck/shoulders: longitudinal data from the Nord-Trondelag Health Study. Am J Epidemiol 174:267–273 25. Brooks C, Siegler JC, Cheema BS, Marshall PWM (2013) No relationship between body mass index and changes in pain and disability after exercise rehabilitation for patients with mild to moderate chronic low back pain. Spine 38:2190–2195 26. Marshall PWM, Murphy BA (2006) Evaluation of functional and neuromuscular changes after exercise rehabilitation for low back pain using a Swiss ball: a pilot study. J Manip Physiol Ther 29:550–560 27. Marshall P, Murphy B (2010) Delayed abdominal muscle onsets and self-report measures of pain and disability in chronic low back pain. J Electromyogr Kinesiol 20:833–839 28. Fairbank JCT, Mboat JC, Davies JB, O’Brien JP (1980) The Oswestry low back pain disability questionnaire. Physiotherapy 66:271–273 29. Roland M, Morris R (1983) A study of the natural history of back pain. I: development of a reliable and sensitive measure of disability in low-back pain. Spine 8:141–144 30. Roland M, Fairbank J (2000) The Roland-Morris Disability Questionnaire and the Oswestry Disability Questionnaire. Spine 25:3115–3124 31. Ostelo RWJG, Deyo RA, Stratford P, Waddell G, Croft P, von Korff M, Bouter LM, de Vet HC (2008) Interpreting change scores for pain and functional status in low back pain: towards international consensus regarding minimal important change. Spine 33:90–94
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ORIGINAL ARTICLE
Has overweight any influence on the effectiveness of conservative treatment in patients with low back pain? Dorothea Daentzer • Tina Hohls • Christine Noll
Received: 18 April 2014 / Revised: 12 June 2014 / Accepted: 13 June 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract Purpose Low back pain and overweight are two relevant disabling health conditions. To date, there is a lack of information about the effectiveness of nonoperative therapy in persons with overweight and low back pain. The aim of our study was to evaluate if overweight has any influence on the effectivity of conservative treatment in patients with low back pain during a mid- to long-term time period. Methods 128 patients with low back pain participated in this study. All of them got an inpatient conservative treatment program. The weight status was classified according to the body mass index (BMI) in three weight groups (normal, overweight, obesity). The patients were asked to fill out a standardized questionnaire regarding self-reported pain with the visual analog scale and their disability with the Oswestry Disability Index and the Roland-Morris Disability Questionnaire at four time points (beginning and end of hospital stay and after 5 and 17 months). Results Concerning the short-term results of the three scores, we always observed an improvement of the patients’ condition with statistically significant reduction of pain and disability at discharge. This was true for the total collective as well as for each of the three BMI-groups when considered separately. The pain intensity and disability
D. Daentzer (&) C. Noll Spine Section, Orthopedic Department of Hannover Medical School, Diakoniekrankenhaus Annastift gGmbH, Anna-vonBorries-Str. 1-7, 30625 Hannover, Germany e-mail: [email protected] T. Hohls Clinic for Anesthesiology, Intensive Care and Pain Therapy, Klinikum Nordstadt, Klinikum Region Hannover, Hannover, Germany
were still and mostly statistically significantly decreased in the mid- to long-term follow-up. Regarding the three BMIgroups among themselves, the differences of the data in the pain and disability scores showed generally no statistical significance. Conclusions We conclude for the first time that a conservative treatment program in patients even with chronic low back pain is effective both in a short-term and a midto long-term time period respectively without any significant differences between patients with a normal BMI or with overweight or obesity. Keywords BMI Body mass index Conservative treatment Low back pain Obesity Overweight
Introduction Low back pain is a relevant medical problem affecting 70–85 % of the population at least once during their lifetime [1–5]. Obesity is a prevalent condition and characterized by excess adipose tissue contributing to metabolic dysfunction [6–8]. It has been suggested that obesity may affect pain and disability levels in chronic low back pain and can increase the risk of future chronic low back pain development [9, 10]. Several studies have shown a positive correlation between low back pain and overweight [9, 11– 15]. These findings were supported by the fact that most patients have noticed reduction in low back pain after weight loss, either with a diet or after bariatric surgical procedures [6, 16, 17]. Some authors further showed that people with overweight demonstrate more signs of disc degeneration as a possible cause of low back pain than persons with normal weight [18–20]. In contrast, a systematic literature review found only in 32 % of the studies
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Eur Spine J Table 1 Main diagnosis of the 128 patients (more than one diagnosis could be mentioned because of the possibility of combined pathologies, for example spondylolisthesis plus spinal canal stenosis) Diagnosis
n
%
Degenerative disc disease
78
60.9
Disc protrusion or prolapse
47
36.7
Spondylolisthesis (degenerative or lytic) Spinal canal stenosis
27 27
21.1 21.1
Facet joint arthrosis
27
21.1
Degenerative scoliosis
16
12.5
(21 of 65) a positive association between the body mass index (BMI) or body weight and low back pain [21]. The therapy of choice for patients with low back pain is conservative treatment and mainly exercise except for conditions when surgery is mandatory like in tumorous, traumatic or inflammatory situations [22, 23]. One study even showed a positive effect on chronic low back pain in obese persons who performed exercises for one or more hours per week in contrast to those who were inactive [24]. However, the exact influence of the body weight on patients with low back pain who had a conservative treatment program is already not really known. Only one recently published study investigated the relationship between the BMI and changes in pain and disability resulting from exercise-based chronic low back pain therapy in which the authors found no correlation [25]. But the follow-up in this trial was only 8 weeks, so we do not have any mid- to long-term data to date. Therefore, the aim of our study was to evaluate if overweight has any influence on the effectiveness of conservative treatment in patients with low back pain and to analyze the results during a follow-up period up to 17 months.
Patients and methods 128 patients participated in this study. All of them suffered from low back pain and had a stay as an inpatient. The local Ethical Committee (Hannover Medical School, Hannover, Germany) gave its approval to this retrospective study and to analyze the data which had been routinely collected in all low back pain patients in our clinic. Indication for treatment in the hospital was therapy resistant complaints after conservative therapy under outpatient conditions or exacerbated pain causing immobilization. Inclusion criteria were only degenerative changes of the lumbar spine as well as lytic spondylolisthesis. The main diagnosis was classified according to conventional X-rays, computer tomography or magnetic resonance imaging and
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listed in Table 1. Patients with back pain due to tumorous, inflammatory or traumatic origin had been excluded, as well as persons with urgent reasons for operation such as paresis or intractable pain. Measures All patients had measurements of their body height and weight to calculate the body mass index (BMI, kg/m2) [8]. According to the BMI persons were classified into three groups [8]: Group 1 with BMI \25.0 kg/m2 (normal weight). Group 2 with BMI 25–29.9 kg/m2 (overweight). Group 3 with BMI [29.9 kg/m2 (obesity). The questionnaire included self-reported information regarding the duration of back and leg pain and also data to classify the pain intensity which was determined with the visual analog scale (VAS) as a measuring instrument for the subjective level of pain pointed out in a continuous line between two end points representing no pain ‘‘0’’ (left anchor) and maximal imaginable pain ‘‘10’’ (right anchor) [26, 27]. The self-reported functional impairment was analyzed on the one hand with the Oswestry Disability Index (ODI) as a 10-item questionnaire resulting in a score out of 50 converted to percentage [23, 26–28]. The disability scores of the ODI can be interpreted in the following five grades: 0–20 %: minimal disability. 20–40 %: moderate disability. 40–60 %: severe disability. 60–80 %: crippled. 80–100 %: bed-bound. On the other hand, the Roland-Morris Disability Questionnaire (RM) was used which is a 24-item questionnaire also converted to percentage [29]. The higher the score, the higher is the disability (for example 0 % means no disability, 100 % means severe disability). The VAS, ODI and RM are valid and reliable methods of measuring pain and disability [27, 30]. The participants were instructed to fill out the same questionnaire at four points of time: 1. 2. 3. 4.
At the beginning of hospital stay. At the end of hospital stay (discharge). After a mean follow-up at 5 months. After a mean follow-up at 17 months.
If the patients had not sent back the questionnaires spontaneously after 5 or 17 months, they were remembered by letter or by phone, so that as much as possible forms could be collected until the end of the study duration. Nevertheless, a certain drop out rate had to be noted. A few
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patients stopped their participation because of a lack of compliance and some persons had conversion of the conservative treatment to surgery. Treatment All patients had a standardized conservative treatment program. It consisted of physiotherapy and manual therapy, which was performed daily. Physical procedures as local heat, massage, electrotherapy, and medical bathing were alternatively applied every 2 days. The patients had also daily back therapy training. Medication was individually adapted to the patient’s complaints and pain intensity and consisted of analgesics according to the scheme of the World Health Organization and co-analgesics as muscle relaxants and antidepressants. Furthermore, the patients got local injections in the form of facet joint injections or periradicular therapy based on the underlying pathology. At the time of discharge, the patients were advised to continue the conservative treatment in an outpatient setup. Statistical analyses Statistical analyses were performed using SPSSÒ for Windows (version 14.0, SPSS Inc., Chicago, IL, USA). All analyses were conducted for the total patient collective and for the three BMI-groups separately. Differences in the outcome parameters within the study period at the four time points as well between the three BMI-groups were studied by using the t test. A p value of \0.05 was considered significant.
Results
(72.7 %) at time 3 and 88 (68.8 %) at time 4. All data which were complete to the different moments were included into statistical analysis. Regarding the drop outs there were no statistical significant differences between the three BMI-groups. Many of the patients had chronic complaints with a mean duration of low back pain of 113 months (range 3 weeks to 540 months) and leg pain of 34 months (range 2 weeks to 360 months). The average length of the hospital stay was 9.4 days (range 2–46 days). Outcome data (scores) The results regarding the VAS at the four time points are presented in Fig. 1 for the total study collective and in Table 2 for the three BMI-groups in direct comparison. In the total patient group (Fig. 1), the pain intensity was statistically significantly decreased between time 1 and time 2 (p \ 0.001), time 1 and time 3 (p \ 0.001) and time 1 and time 3 (p \ 0.001). However, the data then showed statistically significant increase between time 2 and time 3 (p \ 0.001) and between time 2 and time 4 (p = 0.004). Concerning the results among the three BMI-groups (Table 2), we did not found any statistically significant differences at each of the four moments. Analogous to this, Fig. 2 and also Table 2 demonstrate the data of the ODI and Fig. 3 and Table 2 the findings of the RM. Regarding the data of the ODI (Fig. 2), we observed statistically significant improvement between time 1 and each of the time points during follow-up (time 1 to time 2 with p \ 0.001, time 1 to time 3 with p = 0.001 and time 1 to time 4 with p \ 0.001). In a similar way, improvement in the RM was seen between the initial time point and time 2 (p \ 0.001) and time 1 to time 3 (p = 0.031) (Fig. 3). Analogous to the findings of the VAS, there were no
Patient characteristics The mean age of the 75 women (58.9 %) and 53 men (41.1 %) was 60.9 years (range 25–88 years). 45 patients (35.2 %) had a normal body weight with a BMI \25.0 kg/ m2 (BMI-group 1). 47 persons (36.7 %) were classified as overweight with a BMI between 25.0 and 29.9 kg/m2 (BMI-group 2). 36 patients (28.1 %) had a BMI [29.9 kg/ m2 and belonged to the obese collective (BMI-group 3). The average BMI of the total study group was 27.5 kg/m2. The data of 40 participants could not be included into the final analysis. 29 of the 128 patients (22.7 %) had a surgical procedure during the follow-up because of therapy resistant symptoms. 11 (8.6 %) persons either had not sent back the questionnaire or had stopped their attendance for any reason. The number of people of whom the data were complete to the four different time points was the following: 128 (100 %) at time 1, 111 (86.7 %) at time 2, 93
Fig. 1 Mean VAS during the follow-up at the four time points in the total study collective. Asterisks means statistically significant differences between two columns connected with a bar
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Eur Spine J Table 2 Mean VAS, ODI (%) and RM (%) and standard deviation during the follow-up at the four time points for the 3 BMI-groups in direct comparison BMIgroup
Time 1
Time 2
Time 3
Time 4
VAS 1
6.8 ± 2.4
3.9 ± 2.8
4.5 ± 2.7
4.3 ± 3.1
2
7.6 ± 2.0
3.9 ± 3.0
5.8 ± 2.8
5.5 ± 2.9
3
7.3 ± 2.0
4.4 ± 2.6
6.2 ± 2.5
6.0 ± 2.2
47.0 ± 19.7
35.2 ± 21.2
36.1 ± 21.7
32.4 ± 20.9
ODI (%) 1 2
49.6 ± 17.6
39.9 ± 20.8
43.0 ± 17.8
37.8 ± 19.3
3
53.0 ± 13.2
44.0 ± 13.3
46.6 ± 15.9
40.9 ± 17.7
1
56.7 ± 23.4
43.3 ± 25.5
48.7 ± 26.9
51.4 ± 26.0
2
55.7 ± 18.7
45.0 ± 22.9
51.6 ± 19.5
49.3 ± 22.5
3
58.3 ± 14.9
48.3 ± 18.9
51.0 ± 18.3
53.3 ± 21.6
RM (%)
Fig. 2 Mean ODI (%) during the follow-up at the four time points in the total study collective. Asterisks means statistically significant differences between two columns connected with a bar
Fig. 3 Mean RM (%) during the follow-up at the four time points in the total study collective. Asterisks means statistically significant differences between two columns connected with a bar
intensity again was significantly reduced between time 1 and time 2 (p = 0.000), but significantly increased between time 2 and time 3 (p = 0.001). Similarly, the data of the ODI are shown in the Fig. 5a– c. Analogous to the VAS, we saw statistically significant decrease both in BMI-group 1 and BMI-group 2 between time 1 and time 2 (each with p = 0.000) and between time 1 and time 4 (BMI-group 1 with p = 0.033, BMI-group 2 with p = 0.001) (Fig. 5a, b). Additionally, the BMI-group 3 had significant improvement between time 1 and time 2 (p = 0.000) and time 1 and time 4 (p = 0.005) (Fig. 5c). The data of the RM are also presented in the Fig. 5a–c. In all three BMI-groups, the disability was statistically significantly reduced only between time 1 and time 2 (BMI-group 1 with p = 0.013, BMI-group 2 with p = 0.000 and BMI-group 3 with p = 0.001).
Discussion statistically significant differences in the ODI and the RM during the follow-up between the three BMI-groups (Table 2). In the Fig. 4a–c the data of the VAS during the followup are presented individually according to the three BMIgroups to point out any statistically significant differences within the same weight category. In the BMI-group 1 (Fig. 4a), we observed a statistically significant decrease of pain intensity between time 1 and time 2 (p = 0.000) and between time 1 and time 4 (p = 0.016). This was the same for BMI-group 2 (time 1 to time 2 with p = 0.000, time 1 to time 4 with p = 0.000) (Fig. 4b). However, pain increase was significant between time 2 and time 3 (p = 0.019). In the BMI-group 3 (Fig. 4c) the pain
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This is the first study to investigate the effectiveness of an inpatient conservative treatment program in patients with low back pain with special interest to the relationship between BMI and therapy-induced changes in self-reported pain and disability. With a distribution of only about onethird (35.2 %) of persons with normal weight and approximately two-thirds (64.8 %) of overweight or obese individuals, the clinical relevance of supernutrition in our probably representative study collective becomes obvious. Concerning the short-term results of the data of the three scores (VAS, ODI and RM), we always observed an improvement of the patients’ condition with statistically significant reduction of the pain and disability at discharge. This was true for the total collective as well as for each of
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Fig. 4 Mean VAS during the follow-up at the four time points individually considered according to the three BMI-groups. a BMIgroup 1, b BMI-group 2, c BMI-group 3. Asterisks means statistically significant differences between two columns connected with a bar
Fig. 5 Mean ODI (%) and RM (%) during the follow-up at the four time points individually considered according to the three BMIgroups. a BMI-group 1, b BMI-group 2, c BMI-group 3. Asterisks means statistically significant differences between two columns connected with a bar
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the three BMI-groups when considered separately. This finding is a clear demonstration of the effectiveness of the stationary conservative treatment intervention even in patients with chronic low back pain and independent of the body weight. Furthermore, the pain intensity and the disability were still and mostly statistically significantly decreased in the mid- to long-term follow-up. It can be concluded, that there is a certain long lasting positive effect of this conservative therapy program. However, it cannot be estimated if this course is only a result of the inpatient treatment or alternatively a consequence of continued exercises in an outpatient basis or a combination of both, because this topic was not the scope of this study. Regarding the three BMI-groups among themselves, the data of the pain and disability scores were generally not statistically significantly different. It means that the condition of all persons was absolutely comparable independent of their body weight to each time point during the follow-up. However, we can state that in most of all data the normal weighted persons (BMI-group 1) showed the lowest pain intensity and disability, and the obese patients (BMI-group 3) demonstrated the highest complaints and functional impairment. In a recently published manuscript which is the only one dealing with a similar problem the relationship between BMI and exercise-induced changes in selfreported pain and disability in patients with chronic low back pain was investigated [25]. The authors had also included 128 persons of whom 77 % were classified as overweight and obese. Clinically meaningful reductions (C30 %) in VAS and ODI after exercise were experienced by 57.8 and 46.9 % of patients, respectively [31]. Their results were similar to our findings with no evidence of a baseline relationship between BMI and pain or disability and no relationship between baseline BMI and changes in pain and disability after exercise. In spite of the excellent comparability of the quintessence between both studies, there are some relevant differences to our evaluation. The longest follow-up in the presented patient group was 17 months in contrast to only 8 weeks in the investigation of Brooks et al. [25] which is a relative short observation period. The initial self-reported pain and disability were clearly higher in our collective with an average VAS of 7.2 and ODI of 49.9 % (meaning severe disability) compared to the patients of Brooks et al. with an average VAS of 3.95 and ODI of 23.65 % (representing moderate disability). The authors consequently conclude that their results should not be generalized or transferred to persons with higher pain or disability levels. Nevertheless, the statements of both studies are the same. First, a conservative treatment intervention in patients with chronic low back pain is effective both in a short-term and a mid- to long-term follow-up period. Second, there is no
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relationship between the BMI and the pain intensity and disability meaning that we can expect a positive effect in patients both with normal weight and even in overweight or obese persons in a similar way.
Limitations of the study One limitation is the fact that we had a drop out rate of 31.2 % until the end of the study which was mainly because of converting to operation in 22.7 % of the patients in case of therapy resistant complaints. Otherwise, we could include all of the patients’ data into statistical analysis until data acquisition had to be stopped. Another criticism is the lack of information about the kind of therapy after discharge. We could not present any data if the patients had continued their conservative treatment, in which intensity they performed their therapy or if they had stopped their intervention program at any time, because this was not the main topic of our study.
Conclusion According to our data we can conclude for the very first time that a conservative treatment program in patients even with chronic low back pain is effective both in a short-term and a mid- to long-term time period without any significant differences between patients with a normal BMI or with overweight or obesity, respectively. Therefore, we should strongly recommend conservative therapy in these persons independent on their body weight. Further research is necessary to get more information about the influence of a relevant weight loss on the pain intensity and disability during conservative therapy in patients with low back pain. Acknowledgments We want to thank Dr. Ludwig Hoy from the Institute for Biometry, Hannover Medical School, Germany, for his excellent support in performing the statistical analyses. Conflict of interest interest.
None of the authors has any potential conflict of
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