Feasibility of using a clinical measure of depression severity to assess treatment impact on total cost of care

Objective

Patient Health Questionnaire 9-item (PHQ9) has become a commonly used clinical measure of depression severity. This study therefore seeks to determine whether reductions in PHQ9 scores (i.e., symptom severity improvement) correspond to cost of care savings from the payer's perspective.

Methods

The study team obtained health insurance claims data and the PHQ9 scores of same individuals among employees of a large academic employer in the United States covering a two-year period from October 2016 to September 2018, limiting the sample to those who had at least two PHQ9 scores in two separate calendar months during a 12-month period, had initial score of 10 or above, and maintained continuous insurance enrollment for the 12-month period. The study team divided the sample into 3 mutually exclusive groups: no improvement within the 12-month period (NI; PHQ9 score remained unchanged or worsened), partial improvement (PI; 1 %–49 % improvement), or clinically significant improvement (CSI; ≥50 % improvement). Regression-adjusted mean total cost of care calculated on a per-member-per-year basis were then compared across the groups.

Results

The results indicated that relative to NI, CSI had incurred 36 % lower total cost of care (p = 0.032). However, no statistically significant association was found between NI and PI.

Conclusion

Although causal interpretations are difficult, these findings suggested clinically meaningful improvements in PHQ9 score are associated with lower total cost of care and that it is potentially feasible to develop a pay-for-performance scheme that align financial incentives with clinical outcomes. However, several barriers currently exist that prevent implementation in real-world settings.