Predictors for response to rehabilitation in patients with hip or knee osteoarthritis: a comparison of logistic regression models with three different definitions of responder.
OBJECTIVE
To identify pre-treatment predictors of who will benefit from a 3-4-week comprehensive rehabilitation intervention in patients with osteoarthritis (OA) of the knee or hip.


METHODS
A prospective cohort study with assessments at admission to the clinic and after 6 months was conducted. Two hundred and fifty patients from the rehabilitation clinic Rehaclinic Zurzach, Switzerland, were included. Three different measures of response to a 3-4-week comprehensive rehabilitation intervention were used: one indirect measure (minimal clinically important difference (MCID) in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) global score=18% improvement), one direct measure (transition question) and a combination of both criteria. Responders were predicted by a sequential logistic regression analysis with nine personal variables, five lifestyle risk factors, seven psychological status variables and the WOMAC global baseline score.


RESULTS
The set of statistically significant predictors was dependent on the definition of response. The comparison of predictors that were statistically significant in any of the prediction models showed similar odds ratios (ORs) for the majority of predictors across three regression models with the different response definitions as dependent variable. Female gender, absence of depressive symptoms (dep), history of complementary medicine (cm) and low comorbidity (com) were the most stable predictors and had ORs above 2.0 (female) and above 1.5 (dep, cm, com) across the three regression models with different response definitions.


CONCLUSIONS
A set of predictors for the outcome of rehabilitation in patients with OA was identified. If these predictors could be confirmed in future research, this knowledge might help to adopt and individualize the treatment of patients who are, at present, less likely to respond.
Weigl
M
M
Department of Physical Medicine and Rehabilitation, University Hospital Munich, Marchioninistrasse 15, 81377 Munich, Germany.
Angst
F
F
Aeschlimann
A
A
Lehmann
S
S
Stucki
G
G
D000368:Aged; D005260:Female; D006304:Health Status; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000453:epidemiology / Q000534:rehabilitation*; D020370:Osteoarthritis, Knee / Q000453:epidemiology / Q000534:rehabilitation*; D017063:Outcome Assessment, Health Care; D011446:Prospective Studies; D012044:Regression Analysis; D012307:Risk Factors; D013557:Switzerland / Q000453:epidemiology