Postoperative muscle loss, protein intake, physical activity and outcome associations

Abstract

Background: Skeletal muscle loss is often observed in intensive care patients. However, little is known about postoperative muscle loss, its associated risk factors, and its long-term consequences. The aim of this prospective observational study is to identify the incidence of and risk factors for surgery-related muscle loss (SRML) after major abdominal surgery, and to study the impact of SRML on fatigue and survival.

Methods: Patients undergoing major abdominal cancer surgery were included in the MUSCLE POWER STUDY. Muscle thickness was measured by ultrasound in three muscles bilaterally (biceps brachii, rectus femoris, and vastus intermedius). SRML was defined as a decline of 10 per cent or more in diameter in at least one arm and leg muscle within 1 week postoperatively. Postoperative physical activity and nutritional intake were assessed using motility devices and nutritional diaries. Fatigue was measured with questionnaires and 1-year survival was assessed with Cox regression analysis.

Results: A total of 173 patients (55 per cent male; mean (s.d.) age 64.3 (11.9) years) were included, 68 of whom patients (39 per cent) showed SRML. Preoperative weight loss and postoperative nutritional intake were statistically significantly associated with SRML in multivariable logistic regression analysis (P < 0.050). The combination of insufficient postoperative physical activity and nutritional intake had an odds ratio of 4.00 (95 per cent c.i. 1.03 to 15.47) of developing SRML (P = 0.045). No association with fatigue was observed. SRML was associated with decreased 1-year survival (hazard ratio 4.54, 95 per cent c.i. 1.42 to 14.58; P = 0.011).

Conclusion: SRML occurred in 39 per cent of patients after major abdominal cancer surgery, and was associated with a decreased 1-year survival.

Fig. 1

Flowchart of inclusion of the MUSCLE POWER STUDY Overview of assessment of eligibility, inclusion and follow-up of patients in the MUSCLE POWER STUDY. MFI, Multidimensional Fatigue Inventory.

Fig. 2

Physical activity and nutritional intake on each postoperative day after major abdominal surgery a Physical activity in median (interquartile range (i.q.r.)) steps taken per day postoperatively, compared between patients with and without surgery-related muscle loss (SRML). b Nutritional intake in median (i.q.r.) grams of protein per kilogram of body weight per day postoperatively, compared between patients with and without SRML. *P <0.05 in intake, compared between patients with and without SRML (Mann–Whitney U test).

Fig. 3

Multivariable Cox proportional hazards regression analyses of 1-year survival after major abdominal surgery compared between patients with and without surgery-related muscle loss Multivariable Cox proportional hazards regression analyses for factors associated with 1-year survival after major abdominal surgery grouped by the presence of surgery-related muscle loss (SRML) within 1 week postoperatively, as shown in Table 4. The multivariable Cox proportional hazard regression analysis was adjusted for age 65 years or older, type of surgery, surgical R status, and postoperative complications according to the Comprehensive Complication Index.