[Has Back Pain Rehabilitation in Germany Improved Since 1990? A Systematic Review with Meta-Analyses and Meta-Regressions].

Purpose: The aim of this study was to examine whether rehabilitation outcomes for back pain, operationalized as pre-post changes, in Germany have improved since 1990 and whether they have reached clinically relevant thresholds.

Methods: Studies reporting changes in pain intensity, depression, catastrophizing, vitality, functional capacity, and days of incapacity for work across at least two measurement points were included. Meta-analyses using standardized mean differences were performed according to the random-effects model, distinguishing between short-, medium-, and long-term effects. Additionally, mean differences were standardized to the scale widths of the respective instruments and combined meta-analytically. A threshold of 15% of the scale width was used to define clinically relevant change. Subgroup analyses explored whether studies published after 2004 demonstrated better rehabilitation outcomes than earlier studies. Meta-regressions with publication year as a moderator variable pursued a similar aim.

Results: A total of 80 studies involving 19,844 participants were included, of which 57% were controlled studies and 5 used usual care as the control group. Meta-analyses showed mild to moderate improvements with high heterogeneity and medium study quality, but - except for a short-term increase in vitality - without achieving clinical relevance. More recent studies reported significantly better short-term improvements in functional capacity compared to older studies (0.21 vs. 0.38, p=0.014). Meta-regressions confirmed this finding. The heterogeneity of the results was considerable and could not be explained by characteristics of the studies, such as baseline status, the age of participants, or the number of study centres. The inconsistency introduces substantial uncertainty into the findings. Furthermore, it points to a deficiency in the uniformity of rehabilitation delivery.

Conclusions: Despite substantial efforts to enhance structural and procedural quality, there is no evidence that the effectiveness of back pain rehabilitation in Germany has improved beyond marginal levels since 1990. Outcomes remain predominantly below the threshold of clinical relevance. There is a persistent lack of robust randomized controlled trials (RCTs) evaluating the absolute effectiveness of these programs.