The past decades have seen an increase in the numbers of patients undergoing lumbar spinal surgery due to degenerative diseases in the lumbar spine. The return to work rates following a lumbar spinal fusion have been reported to be between 35 and 50 percentages one year after the surgery and between 50-63% at 2-3-year after the surgery.
The aim of the current study is to examine the effect of a case manager-assisting rehabilitation program compared to usual physical rehabilitation for patients undergoing a lumbar spinal fusion on functional disability, pain, and return to work. Furthermore, to explore if the case manager-assisted rehabilitation program is cost-effective in a societal perspective compared to usual rehabilitation.
A total of 82 patients were included from Aarhus University Hospital, Denmark, and Region Hospital of Silkeborg, Denmark. Participants were block randomised at each centre. The participants were randomized 1:1 to case manager-assisted rehabilitation (intervention group) or usual physical rehabilitation (control group), by use of sealed envelopes. Both groups received usual physical rehabilitation. The patients in the intervention group meet pre-operatively with a case manager in order to set a plan for their return to daily activities and work. The intervention also included post-surgical meetings, phone meetings, work place visits, or voluntary roundtable meetings.
Statistical analysis:
For the power calculation, the Oswestry Disability Index was used. Based on another study in process at the time of the planning of the study, and in accordance to other research the standard deviation was set to 17 points. With a minimal clinical important difference of 12 points, a power of 80%, and a two sided significance level of 0.05, a total of 66 patients (33 in each group) should be included. I order to account for a 20% lost to follow-up a total om 80 patient should be included.
Data will be entered twice into EpiData and any divergence will be corrected according to the original material. STATA 14.1 will be used for statistical evaluation. The risk of a type 1 error was set to 5%. The data will be analyzed according to the intention-to-treat principle.
I order to compare the two groups a mixed model for repeated measurements with an unstructured covariance matrix will be used to test the effect on Oswestry Disability Index, back pain, and leg pain.
I order to evaluate the patients' return to work following the surgery, the cumulative incidence proportion of time to first spell of 4 weeks of return to work within a 2-year period will be calculated and compared by the log rank test. The relative cumulative incidens of a spell of 4 weeks' return to work will be analysed in a generalized linear regression model using the pseudo values method adjusted for time until old age pension and disability pension.
The primary outcome used in the economic evaluation are functional disability as measured by the Oswestry Disability Index. Furthermore, health-related quality of life was measured by the EuroQol 5-dimensions (EQ-5D) and valued by Danish preference weights in order to calculate Quality Adjusted Life Years (QALY).
The resource use, costs, and outcomes will be analysed as arithmetic means with 95% bootstrapped confidence intervals based on non-parametric bootstrapping (10,000 replicates), and after discounting at an annual rate of 3%. To assess the cost-effectiveness, costs and outcomes will be transformed into a uni-dimensional measure of incremental net benefit for a range of hypothetical values of willingness to pay per unit of effect: incremental net benefit = (EA - EB) * willingness to pay per effect unit - (CA - CB), where C denotes costs and E denotes effects with A and B referring to comparators.
The study protocol was approved by the Danish Data Protection Agency (J.nr.2010-41-444), and the local Ethical Committee (J.nr.M-20100038)
