Association between constipation and incident chronic kidney disease in the UK Biobank study

Despite previous studies supporting a close relationship between constipation and chronic kidney disease (CKD), the potential impact of constipation on incident CKD and the role of laxatives remains uncertain. We analyzed longitudinal data from the UK Biobank, which links baseline assessment data with follow-up data from hospital episode statistics and general practice records. Constipation was defined with diagnostic codes or regular use of laxatives at baseline as reported in the questionnaire. Cox proportional hazard models were used to evaluate the association between constipation and incident CKD. After excluding individuals with pre-existing CKD or missing covariates, 118,020 participants with general practice follow-up data were included in the main analysis. Over a median follow-up of 7.4 years, 6,833 (5.8%) patients developed CKD. Constipation was significantly associated with increased risk of CKD development in the multivariable adjusted models (hazard ratio [HR] 1.51, 95% confidence interval [CI] 1.37-1.67) for ICD-defined constipation, HR 1.34, 95% CI 1.23-1.47 for constipation defined by ICD codes or laxative use). Patients with ICD-defined constipation, even when taking laxatives, were found to have a higher risk of incident CKD than those without constipation (HR 1.42, 95% CI 1.08-1.85). We found no moderating effects of laxative use on the association between constipation and incident CKD. Constipation is independently associated with incident CKD in the large population-based longitudinal cohort. These findings highlight constipation as a potential risk factor or predictor of CKD development. Further research is warranted to elucidate the role of laxatives in controlled study designs.