Changes in Medication Management After a Diagnosis of Cancer Among Medicare Beneficiaries With Diabetes.

PURPOSE

A new cancer diagnosis commonly initiates a cascade of health care decisions that have potentially important consequences for management of other chronic conditions such as diabetes. We sought to determine whether a new cancer diagnosis is associated with changes in medication adherence among Medicare beneficiaries with diabetes, and whether the relationship is affected by life expectancy and generosity of drug coverage.

METHODS

The study population was drawn from a 5% random sample of Medicare beneficiaries with diabetes enrolled in Medicare Part D in 2007 and 2008. Patients had cancer newly diagnosed between January and December 2007 (n = 4,348) and were compared with a cancer-free control group (N = 28,507) assigned a pseudo-diagnosis date. Adherence (proportion of days covered [PDC]) with oral hypoglycemic agents, renin-angiotensin-aldosterone system inhibitors, and statins was tracked for 6 months before and after the diagnosis date. Multivariable regression models assessed the independent impact of a cancer diagnosis, life expectancy (proxy measure: died 7 to 12 months after index date), and coverage generosity (proxy measure: low-income subsidy recipient) on PDC, controlling for individual characteristics.

RESULTS

Relatively larger declines in medication adherence (3 to 5 percentage points; P < .001) were observed overall for patients with cancer versus controls. Short life expectancy was associated with between 8% and 11% lower PDC (P < .001) in the cancer subgroup relative to controls. Low-income subsidy status had no differential effect on changes in drug adherence.

CONCLUSION

A cancer diagnosis among patients with diabetes reduced adherence with evidence-based medications, particularly if patients' life expectancy was short.