Adherence to diabetes treatment guidelines and diabetes-related complications: a federated meta-analysis of 90,000 patients with newly diagnosed diabetes

The objective of this study was to characterise professionals’ adherence to the Spanish Network of Diabetes Study Groups in Primary Health Care treatment algorithm for type 2 diabetes and to assess the association of this adherence with diabetes-related complications. A federated meta-analysis was designed across four Spanish regions. Adherence was measured using conformance checking, whereby observed treatment patterns were compared with the treatment algorithm. Cohort-specific analyses, stratified by clinical condition, included both linear mixed-effects models to examine the relationship between patient-level factors and adherence, and time-dependent Cox regression models to examine the relationship between adherence and diabetes-related complications. The study included over 90,000 patients with newly diagnosed type 2 diabetes. Patients’ sociodemographic factors influenced adherence heterogeneously. Health professionals adhered more closely to the treatment algorithm for male patients than for female patients for four out of the six clinical conditions considered (obesity, frailty, chronic kidney disease and cardiovascular disease). For patients with obesity, health professionals also adhered more closely to the algorithm for those in the highest socioeconomic category (annual income of 18,000€ and above) than for those in the lowest category (below 18,000€). The resulting pooled hazard ratios for adherence to the treatment guideline were 0.50 (95% CI 0.40, 0.62) for patients with obesity, 0.62 (95% CI 0.53, 0.72) for patients with frailty, 0.05 (95% CI 0.02, 0.13) for patients with chronic kidney disease, 0.15 (95% CI 0.06, 0.37) for patients with heart failure, 0.15 (95% CI 0.09, 0.25) for patients with cardiovascular disease and 0.18 (95% CI 0.14, 0.22) for patients without these conditions. Therefore, adherence to the treatment algorithm was associated with lower risk of diabetes-related complications.