Abstract
Background
Recent parity legislation will require many insurers and the federal Medicare program to reduce mental health copayments, so that they are equivalent to copayments for other covered services. The effect of changes in mental health cost sharing has not been well studied, particularly among elderly populations.
Objective
To examine the consequences of increasing and decreasing copayments on the use of outpatient mental health services among the elderly.
Research Design
Difference-in-differences (DID) design comparing the use of outpatient mental health care in Medicare plans that changed mental health copayments compared with concurrent trends in matched control plans with unchanged copayments.
Study Population
A total of 1,147,916 enrollees aged 65 years and older in 14 Medicare plans that increased copayments by ≥25%, 3 plans that decreased copayments by ≥25%, and 17 matched control plans with unchanged copayments.
Results
In 14 plans that increased mental health copayments from a mean of $14.43 to $21.07, the proportion of enrollees who used mental health services remained at 2.2% in the year before and year after the increase (adjusted DID, 0.1 percentage points; 95% confidence interval, 0.0–0.1). Among 3 plans that decreased copayments from a mean of $25.00 to $8.33, utilization rates were 1.2% before and after the decrease (adjusted DID, 0.1 percentage points; 95% confidence interval, −0.2 to 0.3). Stratified analyses by age, gender, race, and presence of a disability yielded similar results.
Conclusions
Few older adults in managed care plans used outpatient mental health services. Among this population, increasing or decreasing mental health copayments had negligible effects on the likelihood of using outpatient mental health care.
Keywords: Cost sharing, mental health services/utilization, health insurance benefits, Medicare, managed care
Cost sharing, the practice of requiring patients to make out-of-pocket payments to access health services, is a ubiquitous feature of health insurance benefits in the United States. In response to rising health care costs, many insurers have increased cost-sharing requirements for their enrollees.1–4
Cost-sharing requirements have typically been greater for mental health services than for all other types of health services.5 Restricted mental health coverage has been motivated by 2 chief concerns. First, because the RAND Health Insurance Experiment (HIE) found that participants with free care used approximately 4 times as many mental health services (but only twice as many physical health services) as compared with those in the highest cost-sharing group, health insurers have feared that generous insurance benefits may induce patients to overuse mental health services of questionable benefit.6,7 Second, lower mental health copayments may attract enrollees with a high propensity for using mental health services, a phenomenon known as adverse selection.
There have been very few subsequent studies that have investigated the effects of cost sharing on outpatient mental health utilization. Studies of increased mental health cost sharing in 1 health maintenance organization and among retired mine workers are largely consistent with the results of the RAND HIE.8,9 In contrast, reductions in mental health copayments among federal employees demonstrated little effect on mental health service use or spending.10 Therefore, the effect of cost sharing on the use of mental health services remains unclear, particularly among the elderly who were excluded from these previous studies. A better understanding of the effects of cost sharing among the elderly has important health policy implications given recently enacted parity legislation that will require the federal Medicare program and group health plans to reduce cost sharing for mental health services, so that they are equivalent to copayments for other covered health services. Furthermore, the Affordable Care Act will require insurance parity in all health plans offered in state-based health insurance exchanges.
We therefore examined the effect of changing copayments for mental health outpatient care on the use of mental health services in a large, nationally representative cohort of elderly Medicare enrollees in managed-care plans. Using a quasi-experimental design, we compared changes in the use of mental health outpatient services in Medicare managed care (MMC) plans that increased or decreased copayments for ambulatory mental health care with concurrent trends in control plans—similar MMC plans that did not change outpatient mental health copayments.
METHODS
Data Sources and Study Population
From the Centers for Medicare and Medicaid Services’ Healthcare Effectiveness Data and Information Set (HEDIS) we acquired individual-level data for enrollees between 2001 and 2007. We linked the HEDIS data to the Medicare enrollment file to obtain information on patient demographics and to the Medicare Plan Finder data to obtain information on insurance benefits and required cost sharing. We acquired the organizational characteristics of included health plans from the InterStudy Competitive Edge database or by contacting health plans directly.
We analyzed 252 distinct plans with the same cost-sharing requirements for outpatient mental health services across all insurance products. From these, we identified 22 plans with 3 years of reported mental health utilization data, in which the plan required at least 2 years of uniform cost sharing followed by an increase of at least 25% in the third year. We hereafter refer to these plans as case plans. We identified control plans that did not increase mental health ambulatory copayments for beneficiaries over the identical 3-year period. We matched case plans to controls on the basis of census region, model type, and tax status, factors previously shown to be associated with differences in utilization or quality of care.11–13 If a case plan could potentially be matched to more than 1 control plan, we randomly selected 1 control.
Of these 22 case plans, 8 could not be matched to a control plan, leaving a sample of 14 case plans and 14 control plans. We also identified 4 health plans that reported 3 years of continuous mental health utilization data which required at least 2 years of uniform copayments followed by a decrease of at least 25% in the third year. Of these plans, we analyzed 3 plans that could successfully be matched to control plans and reported complete utilization data. Sensitivity analyses of unmatched case plans confirmed that these plans had similar utilization patterns and demographic characteristics to the case plans included in our study. The rates of mental health service used in control plans were similar to utilization rates derived from the entire national sample, which ranged from 2.0% to 2.1% throughout the entire study period.
After excluding beneficiaries less than 65 years of age, our study population included 612,630 enrollees in 14 case plans and 402,788 enrollees in 14 control plans that increased copayments and 21,334 enrollees in 3 case plans and 111,164 enrollees in 3 control plans that decreased copayments.
Study Variables
The dependent variable for this study was whether an enrollee used outpatient mental health services during the calendar year. Mental health utilization was defined as the proportion of individuals receiving outpatient mental health services, defined by HEDIS as intensive outpatient or partial hospitalization services for mental health conditions. Prescription drugs were not included in this measure. We weighted each enrollee by the number of months he or she was enrolled in the health plan. The primary independent variable was an interaction of 2 terms; an indicator variable for whether a health plan was a case or control plan and an indicator variable for the time period (0 in the year before the change, 1 in the year after the change). Covariates included age (65–74 years, 75–84 years, or older than 85 years), gender, race (white, black, other), and 2 area-level measures of socioeconomic position: the percentage of persons aged 65 years and older in the enrollee’s ZIP code with some college attendance and the percentage of persons aged 65 years and older in the enrollee’s ZIP code with income below the federal poverty limit.
Statistical Analysis
We used a difference-in-differences (DID) design to assess the effect of copayment changes on the proportion of enrollees who received outpatient mental health services. This study design controls for secular trends by subtracting the change in utilization in matched control plans from the concurrent change observed in health plans that increased or decreased copayments. Using PROC GENMOD, we constructed generalized linear models including the primary independent and dependent variables as described previously and adjusting for age, gender, race, and area-level socioeconomic position. We used an indicator variable for the health plan to account for clustering of observations in health plans and generalized estimating equations to account for multiple observations per enrollee over time.
Our main cohort included beneficiaries who were continuously enrolled in their health plan in the year before and the year after the copayment change. In a separate sensitivity analysis, we examined use of mental health services for persons continuously enrolled in their health plan for 3 years (2 years before and the year after the copayment change). Results from this analysis were substantively similar to those from the main cohort and are thus not reported.
To determine whether the effects of cost-sharing changes differed by race, age, gender, or the presence of a disability, we constructed separate models for these groups. To address potential selection effects in response to the copayment increase, we examined baseline utilization rates among enrollees who disenrolled from case and control plans, and compared these rates with baseline utilization among persons who were continuously enrolled in their MMC plan.
We determined whether the effects of increased cost sharing were significantly greater among plans increasing their cost-sharing requirements by larger relative amounts. Because of a modest sample of health plans, we stratified plans into the following 2 groups: plans increasing their copayments by greater than or equal to 50% relative to the previous year and plans increasing cost sharing between 25% and 50% relative to the previous year. Because of the relatively small number of MMC plans, we were unable to match plans based on the initial copayment amounts. We performed a stratified analysis of case-control pairs in which the initial copayment amount in the case plan differed by <25%, 25% to 50%, and >50% from that in the control plan. We identified 4 case-control pairs where the initial copayment differed by less than 25%. Therefore, the small number of plans limited the ability to detect statistically different utilization trends within that stratum. Finally, we examined the heterogeneity of DID estimates among each of the 14 matched case-control pairs of insurance plans, increasing copayments to ensure that our overall estimate was not being driven by the larger plans within our sample. All analyses were performed using SAS 9.2 (Cary, NC); results are reported with 2-tailed P values significant at the alpha <0.05 level and confidence intervals (CIs) when appropriate. The Brown University Human Research Protections Office and the Centers for Medicare and Medicaid Services Privacy Board approved the study protocol.
RESULTS
Effects of Increased Mental Health Copayments
In case plans that increased copayments, mean mental health copayments increased from $14.43 (interquartile range [IQR], $10.00–$20.00) to $21.07 (IQR, $15.00 – $25.00), an approximately 50% relative increase. Mean copayments in control plans were unchanged at $21.43 (IQR, $17.50–$25.00). The demographic characteristics of enrollees in case and control plans are shown in Table 1.
TABLE 1.
Enrollee Characteristics in Case and Control Medicare Plans
| Variables | Case Plans That Increased Copayments (N = 306,315) |
Matched Control Plans (N = 201,394) |
Case Plans That Decreased Copayments (N = 10,667) |
Matched Control Plans (N = 55,582) |
|---|---|---|---|---|
| Age, yr* (SD) | 74.5 (7.1) | 74.8 (6.8) | 74.6 (6.7) | 75.5 (6.7) |
| Sex | ||||
| Female (%) | 59 | 59 | 66 | 60 |
| Race (%) | ||||
| White | 94 | 85 | 65 | 74 |
| Black | 2 | 7 | 28 | 23 |
| Other | 4 | 8 | 7 | 4 |
| Income below federal poverty level (%) |
8 | 9 | 13 | 10 |
| College attendance (%) | 37 | 37 | 30 | 34 |
Percentages may not sum to 100 because of rounding.
Age in the year before copayment change.
SD indicates standard deviation.
In case plans that increased copayments, the proportion of enrollees who used mental health services remained at 2.2% in the year before and the year after the increase (Table 2). In control plans, the proportion of enrollees using mental health services decreased slightly from 1.4% to 1.3% over time. There were no significant between-group differences in overall changes in utilization.
TABLE 2.
Use of Outpatient Mental Health Services in Case and Control Plans
| Case Plans That Increased Copayments |
Control Plans | |||||||
|---|---|---|---|---|---|---|---|---|
| Adjusted Difference- in-Differences Estimate (95% CI) (Percentage Points) |
||||||||
| Variable | Year Prior to Change (%) |
Year After Change (%) |
Change In Percentage Points |
Year Prior to Change (%) |
Year After Change (%) |
Change in Percentage Points |
Unadjusted Difference- in-Difference Estimate (Percentage Points) |
|
| Proportion of enrollees using outpatient mental health services |
2.2 | 2.2 | 0.0 | 1.4 | 1.3 | −0.1 | 0.1 (0.0 to 0.1) | 0.1 (0.0 to 0.1) |
|
Case Plans That Decreased Copayments |
Control Plans |
|||||||
| Proportion of enrollees using outpatient mental health services |
1.2 | 1.2 | 0.0 | 1.8 | 1.7 | −0.1 | 0.1 (−0.2 to 0.3) | 0.1 (−0.2 to 0.3) |
CI indicates confidence interval.
Table 3 indicates that there were no significant changes in mental health utilization in stratified analyses by gender, race, age, or presence of a disability. Enrollees who disenrolled from plans after cost-sharing increases were more likely to have used outpatient mental health services than those remaining enrolled (2.8%–2.2%; P < 0.01); however, this trend was also evident in concurrent control plans (1.7%–1.4%; P < 0.01).
TABLE 3.
Adjusted Difference-in-Difference Estimates for Plans That Increased and Decreased Mental Health Copayments, by Age, Sex, Race, and Disability*
| Variable | Copayment Increasing Plans Difference-in- Differences Estimate (95% CI) |
Copayments Decreasing Plans Difference-in- Differences Estimate (95% CI) |
|---|---|---|
| Ages 65–74 | 0.0 (−0.1 to 0.1) | 0.3 (0.0 to 0.7) |
| Ages 75–84 | 0.0 (−0.1 to 0.2) | 0.1 (−0.4 to 0.5) |
| Ages 85+ | 0.2 (0.0 to 0.5) | −1.6 (−2.7 to −0.5) |
| Males | 0.1 (−0.1 to 0.2) | 0.3 (−0.1 to 0.7) |
| Females | 0.0 (−0.1 to 0.1) | −0.1 (−0.4 to 0.3) |
| White race | 0.1 (0.0 to 0.1) | −0.3 (−0.7 to 0.1) |
| Black race | 0.2 (−0.2 to 0.5) | 0.9 (0.5 to 1.3) |
| Other race | 0.2 (−0.1 to 0.4) | 0.2 (−0.6 to 1.0) |
| Disability as the original reason for Medicare eligibility |
−0.2 (−0.6 to 0.1) | −0.7 (−1.8 to 0.5) |
Estimates are displayed as the adjusted change in case plans minus the concurrent change in control plans.
CI indicates confidence interval.
Figure 1 illustrates that there was no uniform effect of cost sharing among plans as 3 plans showed a small decrease in enrollee utilization, 4 plans exhibited a small increase in enrollee utilization, and 7 plans showed no statistically different change in utilization over time. Among the 7 case-control pairs in which the case plan increased copayments by 50% or more, the adjusted DID was 0.0 percentage points (95% CI, −0.1 to 0.1). Among the 7 case-control pairs in which the case plan increased copayments by less than 50%, the adjusted DID was 0.1 percentage points (95% CI, 0.0–0.3). In stratified analyses, there were no significant DID estimates for case-control pairs in which the initial copayment in the case plan differed by 25% to 50% and >50% from that of the control plan. However, in 4 pairs in which the initial copayment in case and control plans differed by less than 25%, the DID estimate was 0.1 percentage points (95% CI, 0.0–0.3; P = 0.06).
Figure 1.
Heterogeneity of difference–in-differences estimates among case-control plans that increased copayments. Estimates are displayed as the adjusted change in case plans minus the concurrent change in control plans.
Effects of Decreased Mental Health Copayments
In 3 case plans that decreased copayments, mean copayments decreased from $25.00 to $8.33, a relative reduction of 67%. Copayments remained at $30.00 in the 3 matched control plans. Enrollees in case plans had stable utilization rates of 1.2% and utilization among enrollees in control plans decreased from 1.8% to 1.7% over time (Table 2). Among black enrollees, utilization after the decrease in copayment increased from 0.3% to 1.0%, as compared with a small decrease in utilization in control plans from 1.0% to 0.9% (Table 3). The adjusted between group difference estimate was 0.9 percentage points (95% CI, 0.5–1.3). None of the other subgroups demonstrated any significant responsiveness to reductions in copayments.
DISCUSSION
Overview
We examined the consequences of increasing and decreasing copayments for outpatient mental health services among a large national sample of enrollees in MMC plans. Our results suggest that a strikingly small proportion of MMC beneficiaries aged 65 years and older use outpatient mental health services. Furthermore, increasing copayments had no statistically significant effect on the use of mental health services, a finding that holds true for vulnerable populations such as black enrollees and the disabled.
The lack of relationship between cost sharing and changes in outpatient mental health utilization was not related to the proportional magnitude of the increase, as there was no association in plans averaging an increase of 74% in beneficiary copayments. Additionally, we found that decreasing copayments was not associated with changes in the use of mental health services in the overall population; however, we did observe that black enrollees were more likely to use mental health services when cost sharing decreased. Finally, we observed similar patterns of disenrollment in plans that increased copayments compared with matched control plans, suggesting that changes in mental health cost sharing are not associated with substantial adverse selection, the tendency of enrollees with a greater propensity to use health services to opt for lower cost sharing.
Outpatient Utilization
Our estimates finding a low proportion of beneficiaries using mental health services is consistent with previous literature examining utilization rates in elderly populations. 14,15 Virnig et al found that in a cohort of MMC beneficiaries enrolled in 1999, only 2.1% of enrollees used outpatient mental health services.15 Our results suggest that this proportion has been both low and stable for a long time. Nationally representative estimates suggest that approximately 13% of nonelderly adults use outpatient mental health services over the course of a given year.16 The low use of mental health services among MMC beneficiaries is of concern given previous findings, suggesting that approximately 20% of the Medicare-eligible elderly have a diagnosable mental health illness. Previous studies have found that approximately half of elderly persons with mental illness do not seek care for their condition.17–19
Cost-Sharing Increases
Our finding that increasing cost-sharing requirements have little or no effect on enrollee outpatient mental health utilization is not in agreement with the results from previous studies that examined the effects of cost sharing on the use of mental health services. For example, the RAND HIE found that patients in the free care group used twice as many physical health services but 4 times as many mental health services as did patients in the group with 95% cost sharing. However, there are several plausible explanations why the effects are different within our sample. First, a large proportion of current mental health outpatient treatment takes place in primary care settings, limiting the potential effect of changes in cost-sharing requirements for outpatient mental health services.20,21 Also, managed-care organizations employ several additional strategies to reduce the utilization of mental health services that may supersede the effects of cost sharing. For example, prior authorization, primary physician gatekeepers, carve-out of behavioral health care, and utilization review are all strategies that could have important effects upon mental health utilization and are unrelated to cost sharing. Consequently, the small proportion of elderly enrollees using outpatient mental health services may represent a cohort that have overcome significant additional barriers to utilization, thus limiting the potential effect of copayment changes. If this is the case, the relative lack of effect of increased cost-sharing may be unique to outpatient mental health, as previous studies of MMC beneficiaries have found very significant enrollee sensitivity to increases in cost-sharing requirements across other medical services.22,23
Cost-Sharing Decreases
Our finding of little overall effect on utilization is particularly relevant given the uncertainty surrounding the effects of new legislation for mental health parity. These results are consistent with those that suggest that the institution of statewide parity laws had little effect on utilization of services, although some of these analyses have found increased access for groups with low income and high need.24–28 Our results suggest that it is unlikely that the elderly will exhibit a great deal of moral hazard in response to reduced cost-sharing requirements.29 This finding may reassure those concerned that the potential utilization increases resulting from compliance with parity regulations would force some health plans to opt out of providing equal coverage. However, our results also indicate that decreasing cost sharing may not be particularly effective in encouraging those in need of mental health services to seek care. Further investigation is warranted to examine whether cost-sharing decreases may have a selective effect on black enrollees.
Limitations
There are some limitations to this analysis. Chiefly, patients were not randomly assigned to health plans. There could be some selection effects in the type of individuals in plans and their response to cost sharing. We did not see any substantial demographic differences in the demographics between case and control plans or utilization behavior of those switching MMC plans; however, it is possible that additional unmeasured characteristics might have influenced our results. The use of additional health services may compete with the utilization of mental health services, particularly among elderly with multiple chronic conditions. However, information on patient comorbidities or the use of other health services was not available.
MMC beneficiaries have a more favorable health status and lower income than Medicare fee-for-service beneficiaries; therefore, our results may not generalize to the broader Medicare population.30–32 Also, differences in initial copayments might limit the comparability of case and control plans. Our sample also included a limited number of plans that decreased copayments, which would be the main effect of parity legislation. Additionally, our data did not include any definitive information regarding whether enrollees had knowledge of impending changes to their mental health copayments or on other benefits offered by insurance plans such as provider networks or behavioral carve outs.
We were unable to examine the volume of mental health outpatient visits for enrollees, and therefore could not determine whether cost-sharing changes had a selective effect on persons with high use of services. Finally, we could not examine whether there were long-term effects of cost sharing that might take place in the years subsequent to a change in cost-sharing requirements.
CONCLUSIONS
Neither increasing nor decreasing mental health copayments had a significant effect on the use of mental health services among elderly enrollees in MMC plans. This finding may be related to the low proportion of MMC enrollees using outpatient mental health services. Although recently passed legislation will require equal cost sharing for mental and physical health services in group health plans and the Medicare program, our findings suggest that insurance parity will be unlikely to increase substantially the proportion of older adults who receive mental health services.
ACKNOWLEDGMENTS
The authors thank Vincent Mor for helpful comments on a previous version of the manuscript.
C.D. Ndumele was supported by an National Institute of Health Grant (1 R25 GM083270) during the conduct of this research.
Footnotes
The views expressed in this article are those of the authors and do not necessarily reflect the position or policy of the Department of Veterans Affairs or the United States government.
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