Journal of Rehabilitation Medicine 51-1CompleteIssue | Page 72

Effects of multimodal back exercise
Study limitations
Participant randomization was not feasible in this
study, since the back exercise programme represents
a service offering by the insurer to which the insured
are entitled. On the other hand, a very large data-set
was at our disposal (n = 348,000), from which, as a
first step, potential statistical twins were chosen based
on cost and demographic data. The actual adjustment
and selection of the control group participants was
accomplished in a second step using propensity score
matching, a proven procedure in healthcare research for
generating comparable groups. While, due to the lack
of randomization, the internal validity of this study is
less than that of an RCT, the external validity of this
field study designed for comparative effectiveness
research should be higher.
The GCPS data variable cannot properly be regarded
as metrical and normally distributed as required in
parametric procedures. Nevertheless, there are indica-
tions that the intervals between the gradations can be
regarded as approximately equal (Table V). For this
reason, we used parametric procedures for GCPS, as
is common practice for Likert scale items.
The analytical inference methods applied here, ho-
wever, can be used, since appropriately large samples
were available.
These results might be biased by physical and psy-
chological comorbidities, as matching refers to age,
sex, costs (direct medical and direct back disorder) and
work days lost, but not to other physical or psycholo-
gical comorbidities. The basic willingness to engage
in sports (as operationalization of motivation) was
similar in both groups at baseline (sports to baseline:
BE 64.6%, ST 62.9%), but physical and psychological
comorbidities were considered only via global health
costs. The strength and direction of the potential bias is
unclear and needs to be addressed in further research.
ACKNOWLEDGEMENTS
Funding: The study was commissioned and funded by AOK
Baden-Wuerttemberg.
Conflicts of interest: Gerhard Müller, Manuela Pfinder, Mi-
chael Clement, Andreas Kaiserauer, Guido Deis, Timm Waber
are employed by the sponsor, AOK Baden-Wuerttemberg;
Stefanie Rieger and Dana Schwarz work for ITSCare (financed
by the AOK Baden-Wuerttemberg public health insurance com-
pany), Michael Straif and Klaus Bös received consulting fees.
REFERENCES
1. Vos T, Barber RM, Bell B, Bertozzi-Villa A, Biryukov S, Bol�-
liger I, et al. Global, regional, and national incidence, pre-
valence, and years lived with disability for 301 acute and
chronic diseases and injuries in 188 countries, 1990–2013:
a systematic analysis for the Global Burden of Disease
Study 2013. Lancet 2015; 386: 743–800.
69
2. Hoy D, Bain C, Williams G, March L, Brooks P, Blyth F, et al.
A systematic review of the global prevalence of low back
pain. Arthritis Rheum 2012; 64: 2028–2037.
3. Andersson GB. Epidemiological features of chronic low-
back pain. Lancet 1999; 354: 581–585.
4. Biering-Sørensen F. A prospective study of low back pain
in a general population. I. Occurrence, recurrence and
aetiology. Scand J Rehab Med 1982; 15: 71–79.
5. Maetzel A, Li L. The economic burden of low back pain: a
review of studies published between 1996 and 2001. Best
Pract Res Clin Rheumatol 2002; 16: 23–30.
6. Kohlmann T, Schmidt CO. Epidemiologie des Rückensch-
merzes. Lendenwirbelsäule: Ursachen, Diagnostik und
Therapie von Rückenschmerzen. Munich: Urban und
Fischer; 2005: 3–13.
7. van Tulder, Maurits W, Koes BW, Bouter LM. A cost-of-
illness study of back pain in The Netherlands. Pain 1995;
62: 233–240.
8. Torstensen TA, Ljunggren AE, Meen HD, Odland E, Mo-
winckel P, Geijerstam S. Efficiency and costs of medical
exercise therapy, conventional physiotherapy, and self-
exercise in patients with chronic low back pain. A prag-
matic, randomized, single-blinded, controlled trial with
1-year follow-up. Spine 1998; 23: 2616–2624.
9. Kohlmann T. Die Chronifizierung von Rückenschmerzen.
Bundesgesundheitsblatt-Gesundheitsforschung-Gesund-
heitsschutz 2003; 46: 327–335.
10. Hayden J, van Tulder MW, Malmivaara A, Koes BW. Exer-
cise therapy for treatment of non-specific low back pain.
Cochrane Database of Systematic Reviews 2005; 3.
11. Korff M von, Ormel J, Keefe FJ, Dworkin SF. Grading the
severity of chronic pain. Pain 1992; 50: 133–149.
12. Thoemmes F. Propensity score matching in SPSS. arXiv
preprint arXiv:1201.6385 2012.
13. Guo S, Fraser MW, editors. Propensity score analysis:
Statistical methods and applications. 2nd ed. Thousand
Oaks, CA: Sage Publications; 2015.
14. Arbeitsmedizin (BAuA) Sicherheit und Gesundheit bei der
Arbeit 2006–Unfallverhütungsbericht Arbeit. Dortmund:
Bundesanstalt für Arbeitsschutz und Arbeitsmedizin; 2008.
15. Arbeitsmedizin (BAuA). Sicherheit und Gesundheit bei der
Arbeit 2007–Unfallverhütungsbericht Arbeit. Dortmund:
Bundesanstalt für Arbeitsschutz und Arbeitsmedizin; 2009.
16. Arbeitsmedizin (BAuA). Sicherheit und Gesundheit bei der
Arbeit 2008–Unfallverhütungsbericht Arbeit. Dortmund:
Bundesanstalt für Arbeitsschutz und Arbeitsmedizin; 2010.
17. Arbeitsmedizin (BAuA). Sicherheit und Gesundheit bei der
Arbeit 2009–Unfallverhütungsbericht Arbeit. Dortmund:
Bundesanstalt für Arbeitsschutz und Arbeitsmedizin; 2011.
18. Wenig Christina M., Schmidt Carsten O., Kohlmann T,
Schweikert Bernd. Costs of back pain in Germany. Eur J
Pain 2009; 13: 280–286.
19. Kienbacher T, Paul B, Habenicht R, Starek C, Wolf M,
Kollmitzer J, et al. Reliability of isometric trunk moment
measurements in healthy persons over 50 years of age.
J Rehabil Med 2014; 46: 241–249.
20. Denner A. Muskuläre Profile der Wirbelsäule: Springer-
Verlag; 2013.
21. Kilian PRD. Gesundheitsökonomische Evaluation in der
psychiatrischen Versorgungsforschung. Prävention und
Gesundheitsförderung 2008; 3: 135–144.
22. Hoch JS, Smith MW. A guide to economic evaluation:
methods for cost-effectiveness analysis of person-level
data. J Trauma Stress 2006; 19: 787–797.
23. Hoch JS, Briggs AH, Willan AR. Something old, something
new, something borrowed, something blue: A framework
for the marriage of health econometrics and cost- effecti-
veness analysis. Health Econ 2002; 11: 415–430.
24. Stinnett AA, Mullahy J. Net health benefits: a new fram-
ework for the analysis of uncertainty in cost-effectiveness
analysis. Med Decis Making 1998; 18: 80.
25. Lühmann D, Stoll S, Burkhardt-Hammer T, Raspe H. Prä-
vention rezidivierender Rückenschmerzen - Präventions-
J Rehabil Med 50, 2018