Associations between cataract and multimorbidity: a cross-sectional study of 23,089 adults from Spain

Background: Little is known about the association between cataract and multimorbidity. Therefore, the aim of the present study was to examine the relationship between cataract and chronic conditions and multimorbidity in a large representative sample of Spanish adults. Methods: This study used data from the Spanish National Health Survey 2017, a cross-sectional sample of 23,089 adults aged ≥15 years from Spain [54.1% female; mean (standard deviation) age 53.4 (18.9) years]. Cataract and 30 other physical and mental chronic conditions were self-reported. Multimorbidity was defined as the presence of at least two physical and/or mental chronic conditions (excluding cataract). Control variables included sex, age, marital status, education, smoking, and alcohol consumption. Multivariable logistic and negative binomial regression analyzes were conducted to assess associations. Results: The prevalence of cataract and multimorbidity was 12.5% and 56.5%, respectively. All chronic conditions were significantly more frequent in individuals with than in those without cataract. Overall, there was a positive relationship between cataract and multimorbidity [odds ratio (OR) = 2.77; 95% confidence interval (CI): 2.39–3.21]. In addition, cataract was significantly associated with the number of chronic conditions in the whole population [incidence rate ratio (IRR) = 1.34; 95% CI: 1.29–1.38]. Conclusions: Cataract is positively associated with chronic conditions and multimorbidity in adults. Interventions specifically designed for those with cataract to reduce or manage co-occurring chronic conditions and multimorbidity are urgently required.