Cost-Effectiveness of School Urinary Screening for Early Detection of IgA Nephropathy in Japan

The evidence for and against screening for chronic kidney disease in youths who are asymptomatic is inconsistent worldwide. Japan has been conducting urinary screening in students for 50 years, allowing for a full economic evaluation that includes the clinical benefits of early detection and intervention for chronic kidney disease.

To evaluate the clinical effectiveness and cost-effectiveness of school urinary screening in Japan, with a focus on the benefits of the early detection and intervention for IgA nephropathy, and to explore key points in the model that are associated with the cost-effectiveness of the school urinary screening program.

This economic evaluation with a cost-effectiveness analysis used a computer-simulated Markov model from the health care payer's perspective among a hypothetical cohort of 1 000 000 youths aged 6 years in first grade in Japanese elementary schools, followed up through junior and high school. The time horizon was lifetime. Costs and clinical outcomes were discounted at a rate of 2% per year. Costs were calculated in Japanese yen and 2020 US dollars (¥107 = US $1).

School urinary screening for IgA nephropathy was compared with no screening.

Outcomes were costs and quality-adjusted life-years (QALYs). Cost-effectiveness was determined by evaluating whether the incremental cost-effectiveness ratio (ICER) per QALY gained remained less than ¥7 500 000 (US $70 093).

In the base case analysis, the ICER was ¥4 186 642 (US $39 127)/QALY, which was less than the threshold. There were 60.3 patients/1 000 000 patients in the no-screening strategy and 31.7 patients/1 000 000 patients in the screening strategy with an end-stage kidney disease. Cost-effectiveness improved as the number of screenings decreased (screening frequency <3 times: incremental cost, -¥75 [US $0.7]; incremental QALY, 0.00025; ICER, dominant), but the number of patients with end-stage kidney disease due to IgA nephropathy increased (40.9 patients/1 000 000 patients). Assuming the disutility due to false positives had a significant impact on the analysis; assuming a disutility of 0.01 or more, the population with no IgA nephropathy had an ICER greater than the threshold (¥8 304 093 [US $77 608]/QALY).

This study found that Japanese school urinary screening was cost-effective, suggesting that it may be worthy of resource allocation. Key factors associated with cost-effectiveness were screening cost, the probability of incident detection outside of screening, and IgA nephropathy incidence, which may provide clues to decision-makers in other countries when evaluating the program in their own context.