Objectives: To determine the reliability of volitional and nonvolitional limb muscle strength assessment in critically ill patients and to provide guidelines for the implementation of limb muscle strength assessment this population.
Data Sources: The following computerized bibliographic databases were searched with MeSH terms and keywords or combinations: MEDLINE through PubMed and Embase through Embase.com.
Study Selection: Articles were screened by two independent reviewers. Included studies were all performed in humans and were original articles. The research population exists of adult, critically ill patients or ICU survivors of either sex, and those admitted to a medical, surgical, respiratory, or mixed ICU. A study was included if reliability of muscle strength measurements was determined in this population.
Data Extraction: Data on baseline characteristics (country, study population, eligibility, age, setting and method, and equipment of limb muscle strength assessment) and reliability scores were obtained by two independent reviewers.
Data Synthesis: Data of six observational studies were analyzed. Interrater reliability of the Medical Research Council scale for individual muscle groups varied from “fair” or “substantial” (weighted κ, 0.23–0.64) to “very good” agreement (weighted κ, 0.80–0.96). Interrater reliability of the Medical Research Council-sum score was found to be very good in all four studies (intraclass correlation coefficients, 0.86–0.99 or Pearson product moment correlation coefficient = 0.96). Interrater reliability of handheld dynamometry was comparable between two studies (intraclass correlation coefficients, 0.62–0.96). Interrater reliability of handgrip dynamometry was very good in two studies (intraclass correlation coefficients, 0.89–0.97). Intrarater reliability of handheld dynamometry and handgrip dynamometry was assessed in one study, and results were very good (intraclass correlation coefficients > 0.81). No studies were obtained on reliability of nonvolitional muscle strength assessment.
Conclusions: Voluntary muscle strength measurement has proven reliable in critically ill patients provided that strict guidelines on adequacy and standardized test procedures and positions are followed.