BackgroundAcute sarcopenia is sarcopenia lasting less than 6 months, typically following acute illness or injury. It may impact patient recovery and quality of life, advancing to chronic sarcopenia. However, its development and assessment remain poorly understood, particularly during hospitalisation. This systematic review aimed to elucidate the incidence of acute sarcopenia and examine changes in muscle parameters during hospitalisation.MethodsEighty‐eight papers were included in the narrative synthesis; 33 provided data for meta‐analyses on the effects of hospitalisation on handgrip strength (HGS), rectus femoris cross‐sectional area (RFCSA) and various muscle function tests. Meta‐regressions were performed for length of hospital stay (LoS) and age for all meta‐analyses; sex was also considered for HGS.ResultsAcute sarcopenia development was assessed in four studies with a pooled incidence of 18% during hospitalisation. Incidence was highest among trauma patients in intensive care (59%), whereas it was lower among medical and surgical patients (15%–20%). Time of development ranged from 4 to 44 days. HGS remained stable during hospitalisation (SMD = 0.05, 95% CI = −0.18:0.28, p = 0.67) as did knee extensor strength. LoS affected HGS performance (θ = 0.04, 95% CI = 0.001:0.09, p = 0.045) but age (p = 0.903) and sex (p = 0.434) did not. RFCSA, reduced by 16.5% over 3–21 days (SMD = −0.67, 95% CI = −0.92:−0.43, p < 0.001); LoS or time between scans did significantly predict the reduction (θ = −0.04, 95% CI = −0.077:−0.011, p = 0.012). Indices of muscle quality also reduced. Muscle function improved when assessed by the short physical performance battery (SMD = 0.86, 95% CI = 0.03:1.69, p = 0.046); there was no change in 6‐min walk (p = 0.22), timed up‐and‐go (p = 0.46) or gait speed tests (p = 0.98). The only significant predictor of timed up‐and‐go performance was age (θ = −0.11, 95% CI = −0.018:−0.005, p = 0.009).ConclusionsAssessment and understanding of acute sarcopenia in clinical settings are limited. Incidence varies between clinical conditions, and muscle parameters are affected differently. HGS and muscle function tests may not be sensitive enough to identify acute changes during hospitalisation. Currently, muscle health deterioration may be underdiagnosed impacting recovery, quality of life and overall health following hospitalisation. Further evaluation is necessary to determine the suitability of existing diagnostic criteria of acute sarcopenia. Muscle mass and quality indices might need to become the primary determinants for muscle health assessment in hospitalised populations.
