Background/Purpose: adherence to urate-lowering treatment (ULT) in patients with gout is reported to be lower than 50% in the first year and below 20% at 2-year, and worse than in other chronic conditions such as hypertension, diabetes, or hyperlipidemia. This was to evaluate adherence to ULT both overall and during follow-up, to compare it to the adherence to medications for associated comorbidities, and to explore potential causes for non-adherence to ULT.

Methods: transversal study of a nested cohort of patients in a gout-office hospital setting who were scheduled for a follow-up visit during 6 months in 2016.  General data of patients, along with variables related to gout and to comorbid conditions are systematically retrieved at first visit; prescribed ULT, doses, adherence, and serum urate levels were obtained during the follow-up visits. Adherence was retrieved as medication possession rate (MPR) according to pharmacy offices from government electronic databases (including >98% of the general population).  Also, MPRs of drugs prescribed for hypertension, diabetes (only oral), and hyperlipidemia were obtained; if more than one drug prescribed for any of the previous, the best adherence per comorbidity treatment was entered. Good adherence was considered as MPR>80 per cent of that prescribed, target serum urate (sUA) as <0.36 mmol/L.

Patients are educated at first visit and encouraged to be adherent from baseline through to follow-up visits.

Results: adherence data were available from de 209 patients who were scheduled for a follow-up visit during the observation period; 14 (6.7%) patients did not attend the visit. This sample was formed by 90% male, only 55% had received ULT previous to first visit, median age was 65 years at follow-up visit, 47% and 44% showed poliarticular and tophaceous disease at baseline, respectively. MPR overall showed a median of 89% (IQR 79-94, N= 209) for ULT (72% showed MPR>80), and 89% (IQR 81-94, N= 119), 88% (IQR 79-94, N= 65), and 82% (IQR 77-93, N= 28) for hypertension, hyperlipidemia, and diabetes respectively (p<0.05 only for diabetes).

Adherence was lower for patients who did not attend the scheduled visit (median MPR 58% vs. 86%, MPR > 80, 21% vs. 75%, p<0.01). Adherence was lower during the first year (80%, N=67) compared to 2-3 year period (86%, N=67) or 4 or over (89%, N=75). MPR>80 were 57%, 76% y 81% for the same periods of follow-up, respectively. Good adherence was associated to a rate of target serum urate of 90%, compared to 72% for patients showing MPR<80.

Male gender and un-attendance to scheduled visit were statistically associated to MPR<80 in multivariate analysis; rate of achieving MPR80 was numerically higher with increasing age and overall comorbidity. 

Conclusion: adherence to ULT measured as MPRs in a cohort of educated patients is good, sustained during follow-up, and similarly good to that for comorbid conditions (hypertension, hyperlipidemia, and diabetes); therefore, we cannot blame poor adherence on the patients any more. Avoiding absenteeism could be an opportunity for further improvement.