Actively preparing for major surgery by exercising and improving diet (known as “prehabilitation”) is associated with fewer complications, less time in hospital, and improved recovery and quality of life in adults, finds an analysis of clinical trials published by The BMJ today.

The researchers stress that the certainty of evidence for all comparisons was generally low to very low, but they say prehabilitation based on exercise, nutrition, or exercise combined with other components, may be beneficial.

Existing evidence suggests that prehabilitation can improve outcomes after surgery, but there’s a lack of clarity about which components, or combinations of components, are most likely to be effective.

To address this, researchers in Canada trawled databases for any randomized controlled trial involving adults preparing for major surgery who received prehabilitation interventions or usual care.

They found 186 relevant trials involving 15,684 participants (average age 62; 45% women) that investigated individual or combinations of prehabilitation components (exercise, nutritional, cognitive, and psychosocial support) for seven or more days before surgery.

Critical outcomes of interest were complications up to 30 days after surgery, length of hospital stay, and health related quality of life and physical recovery (based on widely used tests) up to 90 days after surgery.

The trials were of varying quality, but the researchers were able to assess their risk of bias and the certainty of evidence using established tools.

After accounting for other potentially influential factors including surgery type, they found that exercise was associated with a 50% reduced risk of complications compared with usual care, while nutritional support was associated with a 38% reduced risk. Combined exercise, nutritional, and psychosocial support was associated with a 36% reduced risk.

Compared with usual care, combined exercise and psychosocial support was associated with 2.44 fewer days in hospital, while combined exercise and nutritional support was associated with 1.22 fewer days. Individually, exercise and nutrition were associated with 0.93 and 0.99 fewer days, respectively.

Combined exercise, nutritional and psychosocial prehabilitation was most likely to improve health related quality of life and physical recovery. Individually, exercise and nutrition were most likely to improve all critical outcomes.

Although this review was conducted according to best practices and was based on the latest trial evidence, the researchers acknowledge several limitations and stress that the certainty of evidence for all comparisons across all outcomes was generally low to very low due to bias and the high level of variation (heterogeneity) between trials.

However, they say the results for exercise and nutritional prehabilitation were robust after excluding trials with a high risk of bias, “suggesting that prehabilitation based on exercise, nutrition, or exercise combined with other components, may benefit adults preparing for surgery and could be considered in clinical care.”