[Cost-related discontinuation of pharmacological treatment. Mexican Health and Aging Survey 2015-2021]

To describe the frequency of discontinuation of pharmacological treatment among older adults due to cost and to analyze inequalities according to demographic and socioeconomic factors.

Retrospective longitudinal study using data from the Mexican Health and Aging Study 2015, 2018, and 2021. A descriptive analysis and multiyear multiple logistic regression were performed to identify demographic and socioeconomic factors associated with treatment discontinuation due to out-of-pocket cost.

Paying for prescribed medications is common in Mexico (2015: 46.1%; 2018: 46.9%; 2021: 53.2%, considering the total sample), and the amount paid was associated (p <0.001) with treatment discontinuation, which tended to decrease over the period (2015: 11.5%; 2018: 11.6%; 2021: 9.5%), but unequally across socioeconomic level (higher among the poorest), sex (more frequent in women), and type of insurance (higher among older adults without social security or with private insurance). In 2018, educational level and place of residence were associated with treatment discontinuation (more frequent in those with lower education and in rural populations).

Out-of-pocket spending on prescribed medications is common among older adults in Mexico and is associated with treatment discontinuation. Poverty and sex are linked to greater vulnerability to discontinuation, exacerbated by the segmentation of the health system.