We study the strategic relationship between hospital investment and provision of service quality. We use a spatial competition framework and allow investment and quality to be complements or substitutes in patient benefit and provider cost. We assume that each hospital commits to a certain investment before deciding on service quality, and that investment is observable and contractible while quality is observable but not contractible. We show that, under a fixed DRG-pricing system, providers' lack of ability to commit to quality leads to under- or overinvestment, relative to the first-best solution. Underinvestment arises when the price-cost margin is positive, and quality and investments are strategic complements, which has implications for optimal contracting. Differently from the simultaneous-move case, the regulator must complement the payment with one more instrument to address under/overinvestment. We also analyse the welfare effects of different policy options (separate payment for investment, higher per-treatment prices, or DRG-refinement policies).
