Muscle relaxant use and the associated risk of incident frailty in patients with diabetic kidney disease: a longitudinal cohort study

BACKGROUND: Patients with diabetic kidney disease (DKD) are at an increased risk of frailty. The exposure to muscle relaxants frequently leads to adverse effects despite their modest therapeutic efficacy, but whether muscle relaxants predispose users to frailty remains unclear. METHODS: Patients with DKD from a population-based cohort, the Longitudinal Cohort of Diabetes Patients, were identified between 2004 and 2011 (N = 840,000). Muscle relaxant users were propensity score-matched to never-users in a 1:1 ratio based on demographic features, comorbidities, outcome-relevant medications, and prior major interventions. Incident frailty, the study endpoint, was measured according to a modified FRAIL scale. We used Kaplan–Meier analyses and Cox proportional hazard regression to analyze the association between cumulative muscle relaxant use (⩾ 28 days) and the risk of incident frailty. RESULTS: Totally, 11,637 users and matched never-users were enrolled, without significant differences regarding baseline clinical features. Cox proportional hazard regression showed that patients with DKD and received muscle relaxants had a significantly higher risk of incident frailty than never-users [hazard ratio (HR) 1.26, 95% confidence interval (CI) 1.04–1.53]. This increase in frailty risk paralleled that in cumulative muscle relaxant dosages (quartile 1 versus 2 versus 3 versus 4, HR 0.91 versus 1.22 versus 1.38 versus 1.45, p = 0.0013 for trend) and in exposure durations (quartile 1 versus 2 versus 3 versus 4, HR 1.12 versus 1.33 versus 1.23 versus 1.34, p = 0.0145 for trend) of muscle relaxants. CONCLUSION: We found that cumulative muscle relaxant exposure might increase frailty risk. It is prudent to limit muscle relaxant prescription in patients with DKD. PLAIN LANGUAGE SUMMARY: Does cumulative muscle relaxant exposure increase the risk of incident frailty among patients with diabetic kidney disease? Background: Frailty denotes a degenerative feature that adversely influences one’s survival and daily function. Patients with diabetes and chronic kidney disease are at a higher risk of developing frailty, but whether concurrent medications, especially muscle relaxants, aggravate this risk remains undefined. Methods: In this population-based study including 11,637 muscle relaxant users and matched never-users with diabetic kidney disease, we used a renowned frailty-assessing tool, FRAIL scale, to assess frailty severity and examined the incidence of frailty brought by muscle relaxant exposure. Results: We found that users exhibited a 26% higher risk of developing incident frailty compared with never-users, and the probability increased further if users were prescribed higher doses or longer durations of muscle relaxants. Conclusion: We concluded that in those with diabetic kidney disease, cumulative muscle relaxant use was associated with a higher risk of incident frailty, suggesting that moderation of muscle relaxant use in this population can be of potential importance.