Childhood family income and medication use in youth.

Background: Low family socioeconomic position is a well-established determinant of poor health in youth. Much less is known about the social patterning of youth medication use, and the current evidence is mixed. Furthermore, previous studies have not assessed important confounders of the associations. We analyse differences in youth medication use by childhood family income and medication type.

Methods: Administrative register data on full Finnish cohorts born in 1979-2003 (n=1 490 666) and survival analysis were used to assess the risk of using common prescription medications between ages 16 and 20 according to mean household income in ages 11-15, accounting for several observed familial characteristics including parental health. We also compared siblings with discordant childhood income exposures to assess whether any differences are explained by unobserved familial confounding.

Results: For each 10% increase in childhood family income, there was a 0.6%-1.7% increase in the probability of using the most common prescription medications: antibiotics, painkillers, and allergy and asthma medications. In contrast, a 10% increase in childhood income was related to a 2.5% decrease in the probability of psychotropic medication use. In sibling comparisons, childhood income was not associated with any type of medication use.

Conclusion: Apart from psychotropics, the results may indicate medication underuse among youth from low-income families. The sibling comparisons suggest that moderate differences in childhood income are unlikely to cause differences in youth medication use and thus, in contexts of relative income equality, income differences in medication use are likely to reflect other, unobserved, family factors shared by siblings.