# Long-term Impact of Reduced Patient Out-of-pocket Costs on Diabetes Complications

> **NIH ALLCDC U18** · HARVARD PILGRIM HEALTH CARE, INC. · 2021 · $457,417

## Abstract

PROJECT SUMMARY/ABSTRACT
This project seeks to determine whether 3 natural experiments that reduce out-of-pocket costs for diabetes
patients improve acute and chronic diabetes complications over the longer term. These natural experiments
include: (1) employer adoption of preventive drug lists (PDLs) that make diabetes-related medications $0, (2)
state legislation capping patient out-of-pocket costs for insulin, and (3) employer transitions from high-
deductible health plans (HDHPs) with substantial financial barriers for most services to generous low-
deductible plans. Results could provide evidence about actionable interventions at multiple levels that improve
the health of diabetes patients. Studies will leverage a large, national health insurance claims database from
2007-2023 that the research team has refined under previous projects. The Specific Aims of the project are to:
1. Assess 15-year national trends in (a) diabetes complications and (b) uptake of federal, state, and
employer natural experiments of interest. Analyses will assess 2009-2023 trends in acute preventable and
chronic microvascular and macrovascular complications, including stratification by key subgroups of interest.
Measures related to natural experiment uptake will comprise annual PDL adoption, state-level insulin cost
trends, and HDHP to low-deductible plan switches. These analyses will use a longitudinal, calendar time series
design with joinpoints, adjusted for changing demographics, socio-economic status, and co-morbidity.
2. Determine if reducing drug out-of-pocket costs improves diabetes complications. Over 4 follow-up
years, Aim 2a will examine whether employer switches from health savings account (HSA)-HDHPs with high
drug out-of-pocket costs to PDL HSA-HDHPs with $0 preventive drugs reduce acute and chronic diabetes
complications. Aim 2b will assess these outcomes before and after approximately 10 US states limit insulin
cost sharing. Analyses will use a highly rigorous interrupted time series with control series study design and
Aim 2a will also apply a segmented survival with control group design.
3. Determine if reducing outpatient and emergency department out-of-pocket costs improves diabetes
complications. Analyses will assess if switching from HDHPs with high cost sharing for outpatient and
emergency department care to generous low-deductible plans reduces the risk of acute and chronic diabetes
complications over 4 follow-up years. This aim will also use rigorous controlled interrupted time series and
segmented survival designs.
4. Examine the long-term impact of reduced out-of-pocket costs on key diabetes subgroups including
low-income and high-morbidity members. Aim 4 will involve stratifying Aims 2 and 3 analyses by
characteristics such as income, morbidity, race/ethnicity, and diabetes severity. This aim will use the same
study designs as for Aims 2 and 3 but stratified by the factors of interest.

## Key facts

- **NIH application ID:** 10223871
- **Project number:** 5U18DP006527-02
- **Recipient organization:** HARVARD PILGRIM HEALTH CARE, INC.
- **Principal Investigator:** James Franklin Wharam
- **Activity code:** U18 (R01, R21, SBIR, etc.)
- **Funding institute:** ALLCDC
- **Fiscal year:** 2021
- **Award amount:** $457,417
- **Award type:** 5
- **Project period:** 2020-09-30 → 2025-09-29

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10223871

## Citation

> US National Institutes of Health, RePORTER application 10223871, Long-term Impact of Reduced Patient Out-of-pocket Costs on Diabetes Complications (5U18DP006527-02). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10223871. Licensed CC0.

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