Cardiovascular disease (CVD) is a leading cause of early death among patients with advanced chronic kidney disease (CKD). Now a new study of veterans found an association between poor adherence to cardiovascular drugs in the year before dialysis with increased risks of mortality following dialysis initiation.
“Predialysis cardiovascular medication nonadherence is an independent risk factor for postdialysis mortality in patients with advanced chronic kidney disease transitioning to dialysis therapy,” Csaba P. Kovesdy, MD, of Memphis VA Medical Center in Tennessee, and colleagues concluded in a paper published online ahead of print in the American Journal of Kidney Diseases.
Improving medication adherence, on the other hand, might afford patients a longer life, along with timely arteriovenous fistula creation and predialysis nephrology care.
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The team examined CVD medication adherence, all-cause mortality, and cardiovascular mortality among 32 348 mostly white male US veterans who transitioned to dialysis from 2007 to 2011. Pharmacy database analyses were performed to evaluate the degree to which patients followed prescribed dosing instructions to drugs such as angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, calcium channel blockers, beta-blockers, alpha-blockers, direct vasodilators, diuretics (loop and thiazide), aspirin, and statins. They assessed medication adherence by the proportion of days covered by available drugs (PDC) and the medication possession ratio (MPR), the percentage of days covered by dispensed drugs according to refill information (which includes underfills and overfills). The investigators also examined medication persistence, the time from drug therapy initiation to discontinuation.
Over 23 months of follow up, the mortality rate was 283, 294, and 291 patients per 1000 per year for PDC above 80%, above 60% to 80%, and 60% and below, respectively. Compared with patients who had the greatest adherence (PDC above 80%), those with a PDC of 60% to 80% and PDC of 60% or less had higher risks for all-cause mortality by 12% and 21%, respectively. In addition, patients who failed to take their medication consistently had an 11% higher risk of dying from any cause, compared with patients demonstrating medication persistence.
The investigators observed similar trends for cardiovascular mortality, even after adjusting for demographic factors, comorbid conditions (such as diabetes, which affected 69% of patients overall), and laboratory results. They could not account for some factors such as proteinuria or the quality of nephrology care.
Survival also was influenced by several predialysis demographic factors, including age, sex, race socioeconomic status, and comorbid conditions. While some of these attributes cannot be altered, they are useful for risk stratification, according to the researchers.
Adherence to CVD medications should be monitored and reinforced, and “providers should be familiar with available methods for adherence screening and routinely apply them while treating patients with CKD,” Dr Kovesdy and colleagues noted.
As the findings represent white male veterans, they cannot be generalized to the US population as a whole or to women.
