Medicare Accountable Care Organizations and Antidepressant Use in Patients with Depression

Abstract

Objective

This study examined whether Medicare Accountable Care Organization (ACO) programs were associated with early changes in antidepressant use or adherence among beneficiaries with depression.

Methods

Using a difference-in-difference design, claims from Medicare fee-for-service beneficiaries (2009–2013) were compared for ACO patients vs. local control groups. The outcome measures were: total antidepressant days supplied, filling ≥1 antidepressant prescription, and proportion of days covered (PDC) by the supply among antidepressant users (adherence).

Results

Among antidepressant users, ACO contracts were associated with slight differential increases in PDC (.4–.8 percentage points; P≤.03), depending on ACO program and entry year. The proportion of patients with ≥1 antidepressant prescription was unchanged or decreased slightly for ACO patients with depression, such that total supply did not consistently increase.

Conclusions

The Medicare ACO programs were associated with early modest increases in antidepressant adherence but not with increases in the proportion of patients with depression who received antidepressants.

Introduction

In an effort to improve health care quality and reduce spending, Accountable Care Organization (ACO) models are rapidly being adopted as an alternative to fee-for-service payment for commercial and Medicare populations(1). ACOs in Medicare’s Pioneer model and the Medicare Shared Savings Program (MSSP) are eligible to share savings with Medicare if they keep total (Parts A and B) spending for their attributed populations below a financial benchmark set by the Centers for Medicare and Medicaid Services (CMS), while also meeting performance benchmarks based on 33 quality measures. Additionally, both Pioneer ACOs and 2 of 3 tracks in the MSSP share risk with Medicare for spending that is in excess of the financial benchmark. Starting in January 2012, 32 organizations entered the Pioneer ACO program. In April and July of 2012, 114 organizations joined the MSSP, and another 106 joined in January 2013. The MSSP has grown since, and CMS introduced the Next Generation ACO model in 2016(2). Currently, 525 provider organizations participate in Medicare ACO programs, encompassing over 10 million Medicare beneficiaries(3, 4). Prior studies found that Pioneer and MSSP ACOs have had modest success in reducing spending, while maintaining or slightly improving performance on quality measures(5–7).

Patients with behavioral health conditions would be a logical focus of ACO efforts to improve quality and reduce health care spending since medical spending is higher in patients with behavioral health conditions compared to those without(8). If ACOs were to focus on patients with behavioral health conditions, they might begin by targeting patients with depression. There is a robust research base demonstrating that integrating depression care into primary care improves depression outcomes at similar costs(9). Also, depression is associated with non-adherence to medical treatment(10). Therefore ACOs may have incentives to better manage depression in an effort to better manage chronic medical conditions as well. While a recent empirical evaluation of Medicare ACO programs found no increases in recording of depression diagnoses(11), early behavioral health initiatives could have resulted in other changes in depression care. Therefore, the purpose of this research is to examine whether Medicare ACO programs have been associated with changes in antidepressant use and adherence among beneficiaries with depression.

Methods

This study was approved by the Harvard Medical School Institutional Review Board. In each year from 2009–2013, we examined claims data for a 20% random national sample of fee-for-service Medicare beneficiaries who were continuously enrolled in Parts A, B and D during the year and the prior year. In each year, the 20% sample is a 20% sample of the entire Medicare population, including all living members of the prior year’s sample plus a 20% sample of newly eligible beneficiaries. Among these beneficiaries, we identified those who had ≥1 inpatient or ≥2 outpatient claims with a depression diagnosis (ICD-9 codes: 296.2 or 296.3, 300.4, 301.12, 309.1, or 311) in the preceding or concurrent year. We excluded beneficiaries with schizophrenia/psychotic or bipolar disorder spectrum diagnoses (ICD-9: 295, 296.1, 296.4–296.9, 297, 298, 301.11, 301,13). Using previously described methods(11), we attributed each beneficiary to the ACO or non-ACO provider accounting for the most primary care services received by the beneficiary during the year. We were unable to examine substance use disorder comorbidities, as claims with these diagnoses were redacted in compliance with the federal substance use disorder privacy regulation 42 CFR Part 2.

Annually, for each beneficiary with depression we assessed: 1) total days of antidepressant supplied; 2) any antidepressant use (a dichotomous indicator); and, 3) the proportion of days covered (PDC) among antidepressant users—a standard claims-based measure of adherence(12). Total days supplied was defined as the sum of the days covered by antidepressant prescriptions in the study year. Antidepressant medications included: tricyclics, tetracyclics, serotonin-reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, monoamine oxidase inhibitors, bupropion, vortioxetine, and mirtazapine. Beneficiaries without an antidepressant prescription were considered to have zero days covered. Thus, changes in the total days supplied reflected changes in both any use among beneficiaries with depression and adherence among those taking antidepressant medications.

PDC was defined as the total days supplied divided by the number of days the patient was expected to be on antidepressants during the year. The denominator for the PDC measure (“expected” days) equaled 365 for established users or the number of days remaining in the year after the first prescription fill for new users. New users were defined as beneficiaries with depression who did not have an antidepressant prescription fill in the prior 12 months. If the days supplied exceeded the denominator (e.g., due to multiple antidepressants), we truncated the numerator to the denominator so that the PDC could not exceed one. We did not distinguish between antidepressant classes in our measures, thereby considering switches from one class to another as continued adherence to prescribed antidepressants.

Using a difference-in-differences approach and linear regression, we compared changes from before to after the start of ACO contracts for each measure of antidepressant use or adherence among ACO-attributed beneficiaries with concurrent changes among beneficiaries attributed to non-ACO providers (control group). The pre-contract period was 2009–2011 for Pioneer ACOs and ACOs entering the MSSP in 2012, and 2009–2012 for 2013 MSSP entrants. We excluded 2012 as a transition year for the 2012 MSSP entry cohort, since they entered in mid-2012. Thus, we examined post-contract years 2012 and 2013 for Pioneer ACOs and post-contract year 2013 for the 2012/2013 MSSP entrants (pooled to improve power).

Regression models included the following beneficiary demographic and clinical characteristics: age, sex, race/ethnicity, Medicaid coverage, disability, end-stage renal disease, whether beneficiaries were long-term nursing home residents in the prior year, whether beneficiaries had each of 26 conditions in the Chronic Conditions Data Warehouse (CCW) as of the prior year, beneficiaries’ Hierarchical Chronic Condition score (calculated for each beneficiary in each year using diagnoses from the prior year’s claims), and whether they also had diagnoses in the claims for an anxiety disorder (ICD-9: 300) or other psychiatric diagnoses (excluding schizophrenia/psychotic or bipolar disorders) in the prior year. Additionally, we included the proportions of residents: below the federal poverty level, with a high school degree, and with a college degree living in each beneficiary’s area of residence (Zip-Code Tabulation Area), based on U.S. census data. Finally, the regression models included fixed-effects for each combination of hospital referral region and year to adjust for geographic differences between ACO-attributed beneficiaries and the control group and for local changes in antidepressant use in the control group. We used robust variance estimators to account for clustering at the ACO level (for the ACO group) or HRR level (for the control group).

Results

Any differences between the ACO and control groups in observed demographic and clinical characteristics remained stable from the pre-contract to post-contract period, with one notable exception: in 2013 there was a 1.5% differential decrease in beneficiaries in the Pioneer ACOs who qualified for Medicare due to disability (Appendix Table 1). During the pre-contract period, trends in antidepressant use and adherence were similar for the ACO and control groups.

Appendix Table 1.

Characteristics of study sample with depression: comparison of ACOs vs. control group

Beneficiary characteristics	Unadjusted pre-contract mean	Differences between ACOs and control group in pre-contract perioda			Differential change from pre-contract period to post-contract period, ACOs vs. control group
		Pioneer N=19,502 person-years	MSSP 2012 entry cohort N=38,062 person-years	MSSP 2013 entry cohort N=43,008 person-years	Pioneer		MSSP 2012 entry cohort	MSSP 2013 entry cohort
					Post Year 2012 N=7,577	Post Year 2013 N=7,963	Post Year 2013 N=16,112	Post Year 2013 N=14,246
Mean age, years	62.1	.2	1.1	.6	.4	.3	.1	.04
Female sex, %	70.7	2.3***	2.0***	1.5***	−.8	−.6	−1.3**	−.7
Race/Ethnicity, %
Non-Hispanic white	79.0	1.6	−1.1	.9	−.1	−.5	.1	.2
Non-Hispanic black	9.6	−.03	.4	−.5	.2	.2	−.2	−.3
Hispanic	8.5	−.4	.4	−.6	−.7*	−.2	.1	.1
Other	2.9	−1.2*	.2	.2	.6*	.5	0	.02
Medicaid recipient, %	51.1	−3.0*	.8	−3.8***	.7	0	−.2	−.5
Disabled, %b	59.4	−1.0	−2.6*	−2.0*	−.5	−1.5*	−.1	−.3
End-stage renal disease, %	1.4	.2*	.1	−.1*	−.1	−.2	.1	.1
Nursing home resident, %	6.3	−.5	3.3	−1.5***	−0	−.5	−.3	−.2
ZCTA-levelc characteristics, mean
Below FPL, %	10.4	−.5	−.4*	−.6**	.1	−.05	.05	.1
High school degree, %	73.3	2.1**	.7	1.4**	−.1	.2	−.1	−.1
College degree, %	18.3	2.3**	.6	1.3**	−.1	.1	−.1	−.1
CCW conditionsd
Total number, mean	6.1	0	.1	−.1	0	0	.1*	0
≥6 conditions, %	53.0	1.0	1.4	−.5	−.2	−.7	.6	0
≥9 conditions, %	25.2	0	1.4	−.7	.7	.1	.4	−.1
HCCe risk score, mean	1.7	0	0	0	0	0	0	−.01

^*p<.05

^**p<.01

^***p<.001

^aThe pre-contract period took place between 2009–2011 for the Pioneer and 2012 MSSP ACOs and between 2009–2012 for the 2013 MSSP ACOs.

^bIndicates that disability was the original reason for Medicare eligibility.

^cZip code tabulation area from the U.S. census data.

^dConditions assessed from the Chronic Condition Data Warehouse (CCW), including: acute myocardial infarction, Alzheimer’s disease, Alzheimer’s disease and related disorders or senile dementia, anemia, asthma, atrial fibrillation, benign prostatic hyperplasia, chronic kidney disease, chronic obstructive pulmonary disease, diabetes, heart failure, hip/pelvic fracture, hyperlipidemia, hypertension, hypothyroidism, ischemic heart disease, osteoporosis, rheumatoid arthritis/osteoarthritis, stroke/transient ischemic attack, breast cancer, colorectal cancer, endometrial cancer, lung cancer, prostate cancer, glaucoma, and cataracts.

^eHierarchical Condition Category (HCC) score, which predicts annual spending based on diagnoses present in the prior year of claims and is used by Medicare for risk adjustment.

In Pioneer ACOs, there was a significant differential increase in the total days of antidepressants supplied in 2012 (4.2 days, P=.006) constituting a 1.9% increase relative to a baseline mean of 223.7 days supplied. This increase in total days supplied was attenuated in 2013 and was no longer statistically significant (2.2 days; P=.28) (Table 1). The differential increase in total days supplied was driven by a significant differential increase in adherence (PDC) for beneficiaries in Pioneer ACOs in both 2012 (.8 percentage points, or a 1.0% differential increase relative to a baseline mean of 78.1%; P=.007) and 2013 (.9 percentage points, or a 1.2% relative increase; P=.02). For beneficiaries attributed to MSSP ACOs, there was no differential change in total days of antidepressant supplied. For MSSP-attributed beneficiaries, there was a small but significant differential increase in PDC in 2013 (.4 percentage points, or a .5% relative increase; P=.03) and a small decrease in the proportion taking antidepressants (−.5 percentage points, or a .6% relative decrease; P=.04).

Table 1.

Differential changes in antidepressant use and adherence for ACOs compared with control group¹ among beneficiaries with depression

	Pre-contract period2			Differential change from pre-contract period to post period, ACOs vs. control group
	Unadjusted mean (in 2011)	Difference between ACOs and control group	Difference in trend between ACOs and control group	Post year 2012	Post year 2013
Pioneer ACOs3
Total days supplied	223.7	.5	1.1	4.2**	2.2
Any antidepressant use, %	83.0	.2	.2	.3	−.4
Among antidepressant users, proportion of days covered by days supplied, %	78.1	.2	−.1	.8**	.9*
MSSP ACOs4
Total days supplied	223.7	3.4***	−.4	N/A	−.5
Any antidepressant use, %	83.0	.1***	−.1	N/A	−.5*
Among antidepressant users, proportion of days covered by days supplied, %	78.1	.3	−.1	N/A	.4*

^*p<.05

^**p<.01

^***p<.001

¹Control group consists of beneficiaries attributed to providers that did not enter into an ACO contract (either Pioneer or MSSP) with Medicare by 2013.

²The pre-contract period took place between 2009–2011 for the Pioneer and 2012 MSSP ACOs and between 2009–2012 for the 2013 MSSP ACOs.

³Pioneer ACO sample size: pre-contract period N=19,502 person-years, post-year 2012 N=7,577; post-year 2013 N=7,963. Control group pre-contract period N=446,508 person-years; post year 2012 N= 172,487 person-years, 2013 N= 186,701 person-years.

⁴MSSP ACO sample size: 2012 entry MSSP pre-contract period N=38,062 person-years; 2013 entry MSSP pre-contract period N=43,008 person-years; 2012 entry MSSP post-year 2013 N=16,112; 2013 entry MSSP post-year 2013 N=14,246. 2012 entry MSSP pre-contract period control group N=446,508 person-years, 2013 entry MSSP pre-contract period control group N=619,355 person-years; 2012/2013 entry MSSP post-contract period control group N=186,701 person-years.

Discussion

We found consistent early evidence of limited improvements in medication adherence associated with the Pioneer and MSSP ACOs among antidepressant users with depression, but no consistent evidence of changes in the proportion of patients with depression who received antidepressants. These findings contribute to evidence of unchanged or improved quality associated with participation in the Medicare ACO programs(5–7) in general. Our findings are also consistent with recent quantitative research that found limited gains in performance on other behavioral health quality metrics associated with ACOs(11, 13). More generally, the absence of large effects on antidepressant use and adherence in ACOs is consistent with previous documentation that depression is commonly under-recognized and under-treated(14).

Recent qualitative research found that, while many Medicare ACOs had implemented or augmented programs to improve behavioral health care, or depression care more specifically, the degree to which they had done so was mixed(15). Additionally, leaders of Medicare and commercial ACOs have described considerable challenges in improving behavioral health care management, including inadequate data availability for managing behavioral health due to federal and state privacy restrictions that limit information sharing between behavioral health and general medical providers, incomplete SUD data provided by CMS due to restrictions from 42 CFR Part 2, and shortages of mental health care providers(13, 15).

Our study was limited by its observational design, and it is possible that compositional changes in the ACO sample could have contributed to changes in antidepressant use. However, our finding of increased antidepressant adherence was present in both Pioneer and MSSP ACOs and in both post-contract years for Pioneer ACOs, whereas compositional changes that might have biased estimates (mainly the differential decrease in disabled beneficiaries observed in the Pioneer group in 2013) were not consistently detected across programs and post-contract years. Moreover, the ACO programs are voluntary and ACOs likely differ from non-ACO providers in many respects. Thus, our results may not support generalizations about the expected effects of ACO program incentives on later participants. Of greater concern, providers opting to enter the ACO programs could have done so in part because of favorable trends in quality, including antidepressant use and adherence. We found no evidence for such selection bias, however, as trends in antidepressant use and adherence were similar during the pre-contract period for ACOs and the control group. A final limitation is that the substantial dropout from the Pioneer program that began in 2013 could have contributed to the observed attenuation in the effect on total days of antidepressants supplied, but we lacked sufficient power to isolate the effect of program exit on antidepressant use in the latter half of 2013.

Conclusions

Our results indicate evidence of some early modest gains in antidepressant adherence in the Medicare ACO programs. It will be important to understand how the limited gains suggested by our results evolve as organizations gain more experience managing behavioral health care under risk-based ACO contracts.