Diminished rest–activity rhythm is associated with postoperative complications and mortality

BACKGROUND Circadian rhythm disruption, as a modifiable risk factor, has been increasingly recognised for its potential impact on adverse health outcomes, particularly in surgical populations where its implications warrant further investigation. OBJECTIVE(S) To investigate associations between postoperative outcomes and preoperative rest–activity rhythm metrics from accelerometry. DESIGN A cohort analysis of UK Biobank participants undergoing major surgery within 1 year of accelerometer monitoring. SETTING UK Biobank, a large population-based cohort in the United Kingdom. PATIENTS These were 5654 adults (37 to 73 years) completing 7-day preoperative wrist accelerometry. EXPOSURE Rest–activity rhythm relative amplitude was analysed both as a continuous variable and as a categorical variable. For the categorical analysis, a low relative amplitude group was defined as more than 2 standard deviations below the cohort mean: all other participants served as the high relative amplitude group. MAIN OUTCOME MEASURES The primary composite outcome included 30-day postoperative complications and 90-day mortality. Multivariable logistic regression was used to adjust for comorbidities, demographics and surgical risk factors. RESULTS Participants with a low relative amplitude ( n = 225) demonstrated significantly higher rates of adverse outcomes compared with the remainder of the participants ( n = 5429), with an absolute risk difference of 6.1% (9.8 vs. 3.7%), P < 0.001). Multivariable analysis revealed a dose–response relationship: each standard deviation decrease in relative amplitude increased risk by 23% {adjusted odds ratio, aOR: 1.23 [95% confidence interval (CI), 1.06 to 1.42]}. The low amplitude group had double the risk of adverse outcomes compared with the remainder of the participants: adjusted OR: 2.16 (95% CI, 1.25 to 3.73). CONCLUSIONS A lower preoperative circadian relative amplitude is associated with increased postoperative morbidity and mortality. Accelerometry-based circadian monitoring may provide a novel, cost-effective strategy for preoperative risk stratification.