The one-year impact of accountable care networks among Washington State employees

Assessing the effect of a regional integrated care model over ten years using quality indicators based on claims data - the basic statistical methodology of the INTEGRAL project

BACKGROUND

The regional integrated health care model "Healthy Kinzigtal" started in 2006 with the goal of optimizing health care and economic efficiency. The INTEGRAL project aimed at evaluating the effect of this model on the quality of care over the first 10 years.

METHODS

This methodological protocol supplements the study protocol and the main publication of the project. Comparing quality indicators based on claims data between the intervention region and 13 structurally similar control regions constitutes the basic scientific approach. Methodological key issues in performing such a comparison are identified and solutions are presented.

RESULTS

A key step in the analysis is the assessment of a potential trend in prevalence for a single quality indicator over time in the intervention region compared to the corresponding trends in the control regions. This step has to take into account that there may be a common - not necessarily linear - trend in the indicator over time and that trends can also appear by chance. Conceptual and statistical approaches were developed to handle this key step and to assess in addition the overall evidence for an intervention effect across all indicators. The methodology can be extended in several directions of interest.

CONCLUSIONS

We believe that our approach can handle the major statistical challenges: population differences are addressed by standardization; we offer transparency with respect to the derivation of the key figures; global time trends and structural changes do not invalidate the analyses; the regional variation in time trends is taken into account. Overall, the project demanded substantial efforts to ensure adequateness, validity and transparency.

The one-year impact of accountable care networks among Washington State employees

OBJECTIVE

To estimate the impact of a new, two-sided risk model accountable care network (ACN) on Washington State employees and their families.

DATA SOURCES/STUDY SETTING

Administrative data (January 2013-December 2016) on Washington State employees.

STUDY DESIGN

We compared monthly health care utilization, health care intensity as measured through proxy pricing, and annual HEDIS quality metrics between the five intervention counties to 13 comparison counties, analyzed separately by age categories (ages 0-5, 6-18, 19-26, 18-64).

DATA COLLECTION/EXTRACTION METHODS

We used difference-in-difference methods and generalized estimating equations to estimate the effects after 1 year of implementation for adults and children.

PRINCIPAL FINDINGS

We estimate a 1-2 percentage point decrease in outpatient hospital visits due to the introduction of ACNs (adults: -1.8, P < .01; age 0-5: -1.2, P = .07; age 6-18: -1.2, P = .06; age 19-26; -1.2, P < .01). We find changes in primary and specialty care office visits; the direction of impact varies by age. Dependents age 19-26 were also responsive with inpatient admissions declines (-0.08 percentage points, P = .02). Despite changes in utilization, there was no evidence of changes in intensity of care and mixed results in the quality measures.

CONCLUSIONS

Washington's state employee ACN introduction changed health care utilization patterns in the first year but was not as successful in improving quality.