Socioeconomic inequalities, substance use, and chronic multimorbidity in Kiambu and Nakuru counties in Kenya

Multimorbidity, defined as the coexistence of two or more chronic conditions in an individual, is a growing public health concern associated with increased healthcare costs, poorer quality of life, and increased mortality. Substance use, defined as the consumption of alcohol, tobacco, or other psychoactive substances, may influence the development of multimorbidity, but evidence from sub-Saharan Africa remains limited. We examined the prevalence of multimorbidity and its association with substance use, as well as socioeconomic and demographic factors, in two counties in central Kenya. Data were obtained from a household-based, cross-sectional survey using a stratified, two-stage random sampling design. To account for the complex survey design, we employed sample-weighted multivariable analysis using a modified Poisson regression model to estimate adjusted prevalence ratios (aPR) and 95% confidence intervals (CIs) for the associations. Among the 1,484 participants (median age, 36 years), 58% were female, 61% were married, and 52% reported lifetime substance use. Multimorbidity was prevalent in 7.7% of study participants and relatively higher among participants aged 36-45 years (aPR, 4.32 [95% CI, 1.15-16.28], P = 0.031) and 46 years or older (aPR, 12.52; 95% CI, 3.68-42.56; P < 0.001), female (aPR, 1.62 [95%CI, 1.16-2.27]; P = 0.005), those that were divorced or separated (aPR, 2.22 [95%CI, 1.37-3.62]; P = 0.002) and alcohol users (aPR, 1.68 [95%CI, 1.07-2.64]; P = 0.024). Multimorbidity prevalence did not vary significantly by levels of education or income. These findings underscore the need for integrated, community-based approaches to prevent and manage multimorbidity, particularly among older adults, women, and individuals with a history of alcohol use.