Referral compliance and subsequent hospital admissions for COPD and cardiovascular disease in the Netherlands: a data linkage study.

BACKGROUND: General practitioners act as gatekeepers in the Dutch healthcare system, ensuring timely access to specialist care. Few studies have been conducted on compliance with specialty referrals, particularly for conditions like chronic obstructive pulmonary disease (COPD) and cardiovascular disease (CVD), where timely specialist intervention is often important. Therefore, the aim of this study was to gain deeper insight into specialty referral compliance and associated factors, as well as the association between time to compliance and specialist care utilization for COPD and CVD. METHODS: We linked medical claims data from Dutch health insurers and electronic health records from general practice over the period 2015-2020. To analyze specialty referral compliance and healthcare utilization patterns for patients with COPD or at high risk of CVD, referral compliance and healthcare use were assessed over a two-year follow-up period. We adjusted for case-mix factors and time in the dataset. RESULTS: Among COPD patients, 1113 of the 35,606 patients (3.1%) were referred to medical specialist care. Thereof, 5.2% did not comply within one year. Patients that had not depleted their deductibles were more likely to either comply later or not comply altogether. Time to compliance was not associated with hospital admissions, but when compliance was delayed between 1 and 3 months, Intensive Care Unit (ICU) admissions did become more likely. Among patients at high risk of CVD, 2194 of the 130,540 patients (1.7%) were referred to specialist care, with 8.8% remaining non-compliant after one year. Surprisingly, depletion of deductibles increased the likelihood of non-compliance. For both COPD and CVD, age and comorbidities had significant but varying associations with referral compliance. CONCLUSION: Our findings suggest that age, socioeconomic status, financial barriers or certain comorbidities can delay or prohibit compliance, with potential adverse outcomes like ICU admissions. Future research should explore whether non-compliant patients experience worse health outcomes beyond two years or if their conditions are managed without specialist care.