Objectives
An estimated 70% of Canadians with chronic obstructive pulmonary disease (COPD) remain undiagnosed, representing a critical barrier to early intervention to improve disease outcomes. Emerging evidence suggests that opportunistic primary-care based case detection for COPD is a cost-effective solution. We built on a previous cost-effectiveness analysis by evaluating the budget impact of adopting a case detection programme in the general Canadian population.

Methods
This study accords with ISPOR best practice guidelines for budget impact analysis. We used a validated whole disease microsimulation model of COPD in the general Canadian population to evaluate eight case detection strategies implemented during routine primary care visits, varying in their patient eligibility criteria and testing technology. We assessed COPD-related healthcare costs from the healthcare payer perspective over a five-year time horizon (2022-2026) with gradual programme uptake from 5% to 25% by 2026. Costs were determined from Canadian studies and updated to 2021 Canadian dollars. Key parameters were varied in one-way sensitivity analysis.

Results
Compared to no case detection, all strategies resulted in substantial budget expansion. In the most cost-effective scenario at a willingness-to-pay of $50,000/QALY (questionnaire-based testing for all patients ≥40 years), total additional costs were $427 million over five years, with 86% of costs attributed to administering case detection and subsequent diagnostic testing. Furthermore, there were 4.6 million referrals to diagnostic spirometry, 96% of which were false positives. The proportion of individuals with COPD who were diagnosed increased from 30.4% to 37.8% by 2026. Results were most sensitive to case detection uptake in primary care.

Conclusions
A national primary care-based COPD detection programme will require prioritisation by budget holders and significant additional investment in the availability of diagnostic spirometry. Case detection could be effective for reducing the burden of undiagnosed COPD but will depend on successful uptake of the programme in primary care.