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PubMed1998

Interactions between use of and insurance for specialty ambulatory mental health services.

BACKGROUND: There is continuing interest in the effects of coinsurance rates on the use of ambulatory mental health services. Persons who expect to use mental health services may choose coverage with more generous mental health benefits, as such treatment may be expected to be a recurring activity. However, it may also be the case that if the expected need for such services is somehow reflected in lower perceived human capital in the labor market, then persons who have a higher probability of use may face a less generous set of health insurance options. These behaviors imply some simultaneity in the determinants of the coinsurance rate facing an individual and their mental health use. AIM OF THE STUDY: To explore the joint determination of the use of and coinsurance for ambulatory mental health services, using non-experimental data for a nationally representative sample of the non-institutionalized who had employer-based health insurance in the United States. METHODS: I estimate an instrument for the ambulatory mental health coinsurance rate. I then estimate two models of the demand for ambulatory mental health care as a function of the coinsurance rate for this type of care and other factors, one using the actual coinsurance rate and the other using the estimated instrument for the coinsurance rate. RESULTS: In the instrumental equation, an index of the mental distress of the key worker most likely to be the policy-holder has no statistically significant effect on the worker's coinsurance rate. However, a similar measure for other members of the worker's family has a positive and statistically significant effect on the worker's coinsurance rate. In the demand equations, neither the actual coinsurance rate nor its instrument has a statistically significant coefficient. DISCUSSION: Having another family member who may need mental health care results in some effort to seek a health plan with a higher coinsurance rate for such services. While the mental health index for the key worker would motivate the same type of seeking behavior, a higher level for this index for the key worker might also be correlated with a lower level of perceived human capital in a prospective employer's eyes, and this might result in a more restricted set of plan options for mental health care in the labor market. The absence of statistical significant for the coefficients of the actual coinsurance rate and its instrument also provides some limited but suggestive evidence of employer-side selection effects. LIMITATIONS: It was not possible to model the full complexity of health plans. CONCLUSIONS: The discussions of selection bias with regard to mental health insurance and service use should be expanded to include demand-side effects in the labor market, in addition to the supply-side effects on the part of workers that are often considered. IMPLICATIONS FOR HEALTH CARE PROVISION AND USE: It may be difficult to determine the effects on ambulatory mental health care of changes in health insurance provisions. IMPLICATIONS FOR HEALTH POLICY FORMULATION: Caution needs to be used in making estimates of the effects of changes in insurance coverage for ambulatory mental health care. Persons who find their benefits improved may not respond at the rate expected, because initial coinsurance rates are already in part intertwined with expected use. IMPLICATIONS FOR FURTHER RESEARCH: More analyses of the range of selection effects in labor markets and their impacts on health insurance are warranted.

Journal Article↗
PubMed1997

Factors confounding assessment of ambulatory blood pressure monitors, studied during formal evaluation of the Tycos Quiet-Trak.

The credibility of studies assessing ambulatory blood pressure monitoring (ABPM) devices will be enhanced by minimizing opportunities to manipulate the outcome through biased selection of patient volunteers, and by insuring that participants are representative of the target patient population. While subjecting the Welch Allyn Quiet-Trak to the British Hypertension Society (BHS) protocol, we examined the extent to which certain candidate characteristics might influence device assessment. The Quiet-Trak achieved an A grade overall. During its field testing, daytime physical activity measured with a wrist-mounted, piezoelectric accelerometer, influenced significantly the rate of measurement rejection. The tertiles of subjects with highest and lowest levels of daytime physical activity (64 +/- 16 and 35 +/- 10 activity units; P < .001) exhibited significantly different measurement rejection rates (10 +/- 3 and 3 +/- 2 daytime rejects; P < .001)). Most rejected readings occurred during episodes of high physical activity. During static evaluation (Phase V), the level of systolic BP influenced the accuracy of diastolic BP estimation; above 190 mm Hg systolic BP, estimates of diastolic BP differed significantly from manual measurements. Subjects' age and arm circumference influenced neither field nor static evaluation. Retrospective comparison of the study subjects with 120 consecutive ABPM clinic attenders revealed (1) that participants in field testing were younger, had lower BP but were equally active compared with clinic patients; and (2) that Phase V participants exhibited higher systolic (155 +/- 42 v 135 +/- 15 mm Hg; P < .001) but similar diastolic BP levels compared to controls. The reliability of ABPM validation protocols would be enhanced by: (a) incorporation of objective measurement of physical activity during field testing, demonstrating normal levels of activity; (b) requiring that field testing be conducted in representative patients rather than normal volunteers; and (c) a greater focus in both static and field testing on those levels of blood pressure that are relevant in clinical practice.

Blood Pressure Monitoring, Ambulatory↗
PubMed1995

Strategic responses by hospitals to increased financial risk in the 1980s.

OBJECTIVE: This research addresses the following types of responses by hospitals to increased financial risk: (a) increases in prices to privately insured patients (testing separately the effects of risk from the effects of "cost-shifting" that depends on level of Medicare payment in relation to case mix-adjusted cost); (b) changes in service mix offered and selectivity in acceptance of patients to reduce risk; and (c) efforts to reduce variation in resource use for those patients admitted. DATA SOURCES: The database includes a national panel of over 400 hospitals providing information from patient discharge abstracts, hospital financial reports, and county level information over the period 1980-1987. STUDY DESIGN: Econometric methods suitable to panel data are implemented, with tests for pooling, hospital-specific fixed effects, and possible problems of selection bias. PRINCIPAL FINDINGS: The prices paid by private insurers to a particular hospital were affected by the changes in risk imposed by Medicare prospective payment, the generosity of Medicare payment, state rate regulation, and ability of the hospital to bear risk. The risk-weighted measure of case mix did not respond to changes in payment policy, but other variables reflecting the management of care after admission to reduce risk did change in the predicted directions. CONCLUSIONS: Some of the findings in this article are relevant to current Medicare policies that involve risk-sharing, for instance, special allowances for "outlier" patients with unusually high cost, and for sole community hospitals. The first type of allowance appears successful in preserving access to care, while the second type is not well justified by the findings. State rate regulation programs were associated not only with lower hospital prices but also with less risk reduction behavior by hospitals. The design of regulation as a sort of risk-pooling arrangement across payers and hospitals may be attractive to hospitals and help explain their support for regulation is some states.

Cost Allocation↗
PubMed2004

Telephone service interruption weighting adjustments for state health insurance surveys.

Many states rely on telephone surveys to produce estimates of uninsurance. To the extent that people in households without telephones differ from those living in households with telephones, estimates will be biased due to lack of coverage of those in households without telephones. We find the disparity in estimates of uninsurance in the Current Population Survey (all people vs. those living in households without telephones) shows a similar association to the disparity found in the state surveys (all people vs. those living in households with telephone service interruptions). We adjust the state survey weights of those people living in households that experienced telephone interruptions to account for people living in households without telephones and evaluate whether the weighting adjustment for telephone service interruptions is advisable.

Data Collection↗
PubMed2002

Breast cancer and women's labor supply.

OBJECTIVE: To investigate the effect of breast cancer on women's labor supply. DATE SOURCE/STUDY SETTING: Using the 1992 Health and Retirement Study, we estimate the probability of working using probit regression and then, for women who are employed, we estimate regressions for average weekly hours worked using ordinary least squares (OLS). We control for health status by using responses to perceived health status and comorbidities. For a sample of married women, we control for spouses' employer-based health insurance. We also perform additional analyses to detect selection bias in our sample. PRINCIPAL FINDINGS: We find that the probability of breast cancer survivors working is 10 percentage points less than that for women without breast cancer. Among women who work, breast cancer survivors work approximately three more hours per week than women who do not have cancer. Results of similar magnitude persist after health status is controlled in the analysis, and although we could not definitively rule out selection bias, we could not find evidence that our results are attributable to selection bias. CONCLUSIONS: For some women, breast cancer may impose an economic hardship because it causes them to leave theirjobs. However, for women who survive and remain working, this study failed to show a negative effect on hours worked associated with breast cancer. Perhaps the morbidity associated with certain types and stages of breast cancer and its treatment does not interfere with work.

Breast Neoplasms↗
PubMed2003

Difference in the use of preventive services between fee-for-service plans and HMOs: is more better?

OBJECTIVE: Based on the US Preventive Services Task Force recommendations, we studied how health insurance type, ie, fee-for-service (FFS) or health maintenance organization (HMO), affects the utilization of preventive services of differing effectiveness. STUDY DESIGN: Household survey data from the 1993 and 1994 National Health Interview Surveys. METHODS: We compared the use of mammograms, Pap smears, blood pressure measurements, counseling about hormone replacement therapy (HRT), and general physical examinations in FFS plans and HMOs. We used the bivariate probit model to control for selection bias caused by the unobservable factors in the choice of health insurance type. RESULTS: Enrollees in HMOs obtained more Pap smears, blood pressure measurements, mammograms (women 40 to 49 years old), and general physical examinations than enrollees in FFS plans. No significant difference was found between FFS plans and HMOs for the use of mammograms (women aged 30 to 39 years and 50 to 64 years) or HRT counseling. The correlation ratios from bivariate probit estimations indicated no selection bias favoring HMOs; for some preventive services, selection bias favored FFS plans. CONCLUSIONS: Compared with enrollees in FFS plans, persons in HMOs used more preventive services, including less effective ones. Not controlling for selection bias underestimated the HMO effect.

Adult↗
PubMed1990

Documentation of referrals: recording bias due to patient insurance type.

This study explores a possible association between the propensity of primary care physicians to record referrals on special referral forms and the source/mechanism of payment for services. Using a randomly selected sample of visits to University faculty family physicians over a 12-month period, referrals were identified from three sources: progress notes, a special form that was included in the patient's chart, and a computerized list that was generated from the special referral form. A notation in one or more of these sources constituted a referral. Using all three sources, the referral rates were 13.8 referrals per 100 patient encounters for Health Maintenance Organization (HMO) patients, compared with 14.1 for Preferred Provider Organization (PPO) patients and 10.4 for patients with other insurance (p = .83). The progress note in the patient chart was the best source for determining whether a referral had been requested, with approximately 85% documentation. Special forms were not likely to be completed for referrals, especially for non-HMO patients (less than 30% documentation). Thus, reliance on a special form for documentation of referrals would have led to the erroneous conclusion of higher referral rates for HMO patients. The tendency of providers to be more complete in recording referrals of HMO patients (a recording bias) may account for the observed higher rate of referral of such patients in other studies.

Adult↗
PubMed2003

The impact of public voluntary health insurance on private health expenditures in Vietnam.

As a financing mechanism with the potential to raise additional funds for health services, whilst improving access to services amongst the poor, non-profit health insurance has become increasingly attractive to health policy-makers. Using data from a household survey in Vietnam, out of pocket health expenditure are compared between members and eligible non-members of the government-implemented voluntary health insurance scheme. Expenditures are analysed for individuals who sought care during their most recent illness. Using an endogenous dummy variable model to control for bias resulting from self-selection into the scheme, we find that health insurance reduces average out-of-pocket expenditures by approximately 200%. Whilst income inelastic, health expenditures are found to be significantly influenced by an individuals level of income, irrespective of insurance status. Despite this, insurance reduces expenditures significantly more for the poor than for the rich.

Cost Sharing↗
PubMed2006

Unstable inferences? An examination of complex survey sample design adjustments using the Current Population Survey for health services research.

Statistical analysis of the Current Population Survey's Annual Social and Economic Supplement is used widely in health services research. However, the statistical evidence cited from the Current Population Survey (CPS) is not always consistent because researchers use a variety of methods to produce standard errors that are fundamental to significance tests. This analysis examines the 2002 Annual Social and Economic Supplement's (ASEC) estimates of national and state average income, national and state poverty rates, and national and state health insurance coverage rates. Findings show that the standard error estimates derived from the public use CPS data perform poorly compared with the survey design-based estimates derived from restricted internal data, and that the generalized variance parameters currently used by the U.S. Census Bureau in its ASEC reports and funding formula inputs perform erratically. Because the majority of published research (both by academics and Census Bureau analysts) does not make use of the survey design-based information available only on the internal ASEC data file, we argue that the Census Bureau ought to use alternative methods for its official ASEC reports. We also argue that for public use data the Census Bureau should produce a set of replicate weights for the ASEC or release a set of sample design variables that incorporate statistical "noise" to maintain respondent confidentiality (e.g., pseudo-primary sampling units) as other federal government surveys do. This is essential to make appropriate inferences using the ASEC data regarding statistical significance and estimate variance for health policy analysis.

Censuses↗
PubMed2004

For-profit conversion and merger trends among Blue Cross Blue Shield health plans.

Blue Cross and Blue Shield (BCBS) health plans, which insure nearly one in three Americans, historically have operated as local, nonprofit or mutual organizations. However, since the mid-1990s, BCBS plans increasingly have converted to for-profit companies and merged with Blue plans in other states. State insurance regulators, charged with weighing the costs and benefits of conversions and mergers to consumers, often wrestle with the legal complexities of these deals, according to Center for Studying Health System Change (HSC) site visits to 12 nationally representative communities. Although state regulatory scrutiny has slowed the pace of conversions recently, conversion activity is likely to accelerate again as the political and regulatory landscapes shift and plans adapt conversion strategies. The limited evidence available from HSC site visits and conversion proceedings suggests that conversions and mergers have had neither significant negative nor positive effects on consumers.

Blue Cross Blue Shield Insurance Plans↗
PubMed2001

Underutilization of neuropsychology in traumatic brain injury rehabilitation: is managed care to blame?

We evaluated factors determining which individuals received neuropsychological evaluations (NPEs) following traumatic brain injury (TBI). Comprehensive records from a State-wide/sponsored Head Injury Program were followed from 1985--1995 to monitor effects of managed care on provision (or absence) of formal NPEs and ultimately on rehabilitation outcome. Only 26% of 273 individuals received NPEs (within their first three years post-injury). In the years prior to and after large changes in managed care, there were no differences in the provision of formal NPEs. Discriminant analysis identified functional status at discharge from primary rehabilitation and total number of rehabilitation facilities as the two variables that most distinguished those who had received NPEs with 69% classification accuracy. Between group analyses revealed that individuals were more likely to receive NPEs if they were young, involved in liability claims, attended multiple rehabilitation facilities, or had higher functional status at discharge from primary rehabilitation, regardless of the nature or severity of their TBI. Individuals receiving formal NPEs ultimately achieved higher levels of functional independence, suggesting a potential selection bias. Individuals were no more likely to receive NPEs according to insurance status (private versus government assisted) or as a function of the decade of their injury (1980's versus 1990's). It appears that health-care reform has had no deleterious effect on neuropsychologists' ability to provide consultative services for this population, and following TBI, only a discrete sample of individuals receive and benefit from NPEs.

Adolescent↗
PubMed1994

Assessment and control of nonresponse bias in a survey of medicine use by the elderly.

Health services research based on survey data is subject to potentially serious selection bias because observations are typically available only for survey respondents. This study describes a method of assessing and controlling for selection bias in the context of a survey of prescription and over-the-counter drug use by the elderly. A random sample of 6,500 Pennsylvania Medicare enrollees was sent a questionnaire regarding medicine use, insurance coverage, and health status in 1990. Applying a two-stage, limited dependent variable selection model developed by Heckman to baseline Medicare enrollment and utilization data for both respondents (70%) and nonrespondents (30%) allowed us to detect and control for negative and significant nonresponse bias in estimates of prescription drug use. Purchase of over-the-counter medication was free of such bias. The report describes how the Heckman method can be applied in other cases where health services survey samples are generated from program or organizational files that contain person-level data on all members of the sample frame.

Age Factors↗
PubMed2002

Fertility insurance and the sex ratios of malaria and related hemospororin blood parasites.

The sex ratio (z*; proportion of gametocytes that are male) of malaria and related hemospororin blood parasites has been predicted to be related to the inbreeding rate (f) by the simple equation z* = (1 - f)/2. Although there is some empirical support for this prediction, there are several cases where the sex ratio is less female biased or more variable than expected. Here, we present a theoretical model that may be able to explain some of these discrepancies. We show that if low gametocyte densities lead to a danger that female gametes may not encounter any male gametes, then natural selection favors a less female-biased sex ratio as a form of 'fertility insurance' to ensure that female gametes are mated. This model can be applied to a number of situations. In particular, (1) empirical data suggest that the number of gametocyes per blood meal can be low enough to favor fertility insurance in some Plasmodium infections in humans and (2) our model predicts facultative shifting toward less-biased sex ratios in response to immune pressure that reduces gametocyte or gamete survival or mobility, consistent with some recent experimental data from Plasmodium species of birds and mice.

Animals↗
PubMed1997

Analysis of non-response bias in a mailed health survey.

The objective of this study was to identify characteristics of non-respondents and late respondents to a mailed health survey. Persons who returned and those who did not return the questionnaire were compared using health insurance data, which indicated their age, sex, and health care expenditures in the previous year. Insurance and questionnaire data were used to compare early and late survey respondents and to compare categories of non-respondents. Questions covered use of health services, health status, and sociodemographic characteristics. Participants were members of health insurance plans in Geneva, Switzerland, 19-45 years old (n = 1822). Respondents (n = 1424) and non-respondents (n = 398) were of similar age and sex. The proportion of persons who had health care expenditures greater than zero Swiss francs (SFr) was higher among respondents (75%) than among non-respondents (69%, p = 0.03). Among non-respondents, expenditures of persons who explicitly refused to participate (2378 SFr) were higher than expenditures of persons who moved out of Geneva (1085 SFr) or who failed to return the questionnaire (1592 SFr, p = .02). Among respondents, being born in a Switzerland, having completed elementary school, having generated health care expenditures, and reporting good physical health were independent predictors of early response. In conclusion, low response rates to mailed health surveys may result in overestimating the utilization of health services. However, non-respondents did not constitute a homogeneous group, and the strength and even direction of non-response bias depended on the mechanisms of non-response.

Adult↗
PubMed1993

Cognitive risk factors and neuropsychological performance in HIV infection.

Almost all investigations examining the effects of early HIV infection on neuropsychological functioning in homosexual males have excluded subjects with cognitive risk factors such as recreational drug use and head injury. While insuring that results reflect the influence of the virus on cognition, this selection bias limits the ability to generalize findings. Comprehensive neuropsychological evaluations were compared between two groups of homosexual males with a variety of cognitive risk factors. Subjects were 132 HIV seropositive males (108 CDC class II & III and 24 CDC class IVA & IVC2) and 65 HIV seronegative controls. Recreational drug use in the six months prior to exam was found to interact with HIV infection and was associated with selective areas of cognitive decline and a significantly worse overall neuropsychological performance. Although significantly lower functioning in the domains of Verbal Memory and Attention and Speed of Information processing was noted for subjects with CDC class IVA and IVC2 compared to seropositives with CDC class II & III, overall neuropsychological performance was similar in these two groups. At this early stage of HIV infection, we did not find indication of association between neuropsychological performance and decreased immunological status. A history of head injury and recent recreational drug use emerged as primary cognitive risk factors associated with decreased neuropsychological performance. As 50% of our HIV seropositive subjects reported active recreational drug use, this cognitive risk factor in particular may contribute to the appearance of HIV-related cognitive deficits during early stages of HIV infection.

Cognition Disorders↗