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PubMed1983

Occupational morbidity based on social insurance records in Finland.

Daily allowances and invalidity pensions were studied in order to identify morbidity differences between different occupational groups. The highest age-standardized number of daily allowances was found in 'industry' (males 257/1 000, females 373/1 000), and the lowest in administration (males 116/1 000, females 170/1 000). The greatest number of new invalidity pensions for males was also in industry (20.3/1 000), and was 2.9 times as high as in administration. The greatest number of invalidity pensions to females was found in agriculture (18.3/1 000), and was 2.8 times as high as administration. These invalidity pension and daily allowances data measure the morbidity, which is closely associated with socio-economic development and the advances made in the insurance system of the country. Occupational differences in invalidity pensions and daily allowances can be affected by differences in working conditions or by differences in social conditions and life style. The morbidity differences are also affected by selection and survival processes. However, there were also real morbidity differences between occupational groups even after adjusting for bias and errors.

Adolescent↗
PubMed1994

Mental health and substance abuse coverage under health reform.

President Clinton's health care reform proposal articulates a complete vision for the mental health and substance abuse care system that includes a place for those traditionally served by both the public and the private sectors. Mental health and substance abuse services are to be fully integrated into health alliances under the president's proposal. If this is to occur, we must come to grips with both the history and the insurance-related problems of financing mental health/substance abuse care: (1) the ability of health plans to manage the benefit so as to alter patterns of use; (2) a payment system for health plans that addresses biased selection; and (3) preservation of the existing public investment while accommodating in a fair manner differences in funding across the fifty states.

Cost Control↗
PubMed2002

Methods for claims-based pharmacoeconomic studies in psychosis.

Pharmacoeconomic studies using claims data are frequently employed to compare the healthcare costs associated with competing drugs. Different methodological approaches with varying limitations for evaluating claims data are reviewed within the context of psychosis. Intent-to-treat paradigms and mirror-image designs have limitations that can bias comparisons of health resource use and can be addressed through the use of drug treatment episodes. Health resource use is better measured in financial rather than volume amounts, to account for service intensity. However, financial measures reported in claims records need to be carefully chosen. Between-group comparisons are frequently affected by selection bias, and within-group comparisons are often limited by period bias. While selection bias can be addressed by controlling for patient factors such as disease severity, and period bias by controlling for trend, devising appropriate control measures from the limited information in claims data can be challenging. Healthcare data are often skewed, which affects statistical testing. While skewed data are commonly handled through log transformation, this method has serious limitations, potentially distorting pharmacoeconomic comparisons. Determining the most appropriate methods for claims-based data involves careful evaluation of the alternate approaches to best achieve the goals of a pharmacoeconomic investigation.

Antipsychotic Agents↗
PubMed2000

Initial treatment choice in depression: impact on medical expenditures.

OBJECTIVE: The purpose of this study was to examine the economic outcomes associated with initial treatment choice following a diagnosis of depression. METHODS: Insurance claims data were used to classify patients into one of 4 treatment cohorts: no therapy, psychotherapy, drug therapy and combination therapy. Potential sample selection bias was accounted for by using a 2-stage econometric estimation procedure where initial treatment choice was estimated using a multinomial logistic regression model in the first stage, and total and mental healthcare costs were estimated in ordinary least squares regression models in the second stage. Log predicted costs from the second stage were compared to determine the relative costs associated with each cohort. RESULTS: Significant differences (p < 0.008) in total costs were found between the combination therapy (log predicted cost = 9.526) and psychotherapy cohorts (log predicted cost = 8.120) in the analysis that included all observations (n = 9110). In the analysis that included patients who initiated therapy with a non-mental health provider (n = 2673), the drug therapy cohort (log predicted cost = 8.238) was found to be significantly more costly as compared to the no therapy cohort (log predicted cost = 7.788). CONCLUSIONS: These results indicate that after controlling for both observed and unobserved factors, total healthcare costs may be higher in patients who initiate therapy with drug therapy and combination therapy as opposed to no therapy or psychotherapy. In addition, the finding that patients initially receiving psychotherapy alone tend to have higher mental healthcare costs but lower total healthcare costs than other patients may indicate that psychotherapy has an impact on comorbid illness and may subsequently reduce total healthcare costs.

Antidepressive Agents↗
PubMed1991

The problem of participation in the Dutch National Dental Survey.

In 1986 a nationwide dental survey was carried out in the Netherlands. The aims of the study were to assess the prevalence of oral diseases, need and demand for dental care and oral selfcare in the Dutch population aged 15-74 yr. This paper describes the general sampling and analysis procedures to detect selectivity in the participation. Irregular dental attenders seemed to be underrepresented in the final sample. Poststratification was used to overcome this problem of selectivity.

Adolescent↗
PubMed1985

Self-selectivity problems in interregional and interindustry migration in Canada.

This study is concerned with the role that inter-industry mobility plays in the decision to migrate in Canada, and also with the joint impact on earnings of inter-industry and interregional migration, corrected for selectivity bias. The data, for the period 1970-1971, are from a one percent random sample of a micro data base established by the Unemployment Insurance Commission. "Contrary to the commonly held belief that a migrant's decision to change his location is independent of his decision to change his industry of employment, this paper provides evidence that these movements are in fact interrelated."

Americas↗
PubMed2000

Association between abciximab and length of stay in intensive care for patients undergoing percutaneous coronary intervention. A 2-stage econometric model in a naturalistic setting.

OBJECTIVE: To examine the effect of abciximab treatment on intensive care length of stay for patients undergoing percutaneous coronary intervention (PCI). DESIGN AND SETTING: A retrospective study conducted in a naturalistic setting. METHODS: A 2-stage econometric model was used to control for the influence of possible selection bias across categories of patients and for both observable and unobservable factors correlated with each patient's treatment selection and length of stay in intensive care. Multivariate analysis was applied to control for a wide range of factors (patient demographics, insurance provider, health conditions, admission and discharge information, and hospital characteristics) that may influence intensive care length of stay. Retrospective data were obtained from HCIA's Clinical Pathways Database. PARTICIPANTS: Patients (n = 13,364) who were hospitalised in any of 87 hospitals across the US over the period from October 1, 1995 to December 1, 1996. RESULTS: After controlling for high-risk indications and selection bias, results indicated that administration of abciximab was associated with a significantly shorter length of stay in intensive care compared with not administering a GPIIb/IIIa inhibitor (0.45 fewer days; p < or = 0.0001). In a subgroup analysis of patients having an acute myocardial infarction (n = 4793), administration of abciximab was also associated with a significantly shorter intensive care stay (0.27 fewer days; p < 0.0001). CONCLUSION: Results of this study indicate that the administration of abciximab is associated with a reduction in the length of stay in intensive care. This reduction implies potential cost offsets for patients undergoing PCI who receive abciximab.

Abciximab↗
PubMed1987

The role of health practices, health status, and prior health care claims in HMO selection bias.

To examine selection bias in terms of demographics, self-reported health practices, professionally evaluated health status, and prior health care utilization by employees and dependents, we examined health insurance choice between traditional insurance and a health maintenance organization (HMO) by central office employees of a large southwestern utility company. The HMO attracted a relatively younger and female population compared with the traditional plan. We found no difference in health practices and health status measures between the two groups. Consistent with recent studies, the HMO group experienced lower health claims cost the year prior to enrollment compared with persons who remained in the traditional plan. This difference was largely due to dependents' utilization-a factor that should be examined in future studies and considered by those structuring insurance premiums for HMOs and traditional plans.

Adult↗
PubMed1994

Reproductive effects of sodium borates on male employees: birth rate assessment.

OBJECTIVES: The purpose of the study was to investigate potential reproductive effects of sodium borates on occupationally exposed male employees at a large mining and production facility in the Mojave Desert of California. METHODS: The standardised birth ratio (SBR) was used to assess fertility of the male employees. Live births were the measured end point, and the rate of female to male offspring was also assessed. Data were collected through a questionnaire after a series of on site introductory and explanatory meetings with the employees. Initial non-responders were followed up by telephone. Medical insurance records were assessed for those who declined to participate. RESULTS: The questionnaire was a good method of ascertainment for live births. There was no evidence of selection bias in the results. There was a highly significant excess of offspring fathered by the male employees. There was no evidence of a relation between exposure and this excess of offspring, nor were there any temporal differences during the period of observation (> 30 years). Also, there was an excess of the percentage of female offspring fathered by these male employees. This excess of female offspring was not significant. There was no evidence of an exposure relation to sodium borates with this excess of female offspring nor were there any temporal differences. CONCLUSION: Under the conditions studied, there were no adverse reproductive effects of high borate doses as reported from oral ingestion studies in animals.

Adult↗
PubMed2004

Association between SSRI use and hip fractures and the effect of residual confounding bias in claims database studies.

BACKGROUND: Although use of selective serotonin reuptake inhibitor (SSRI) antidepressants has been associated with hip fractures in claims data studies, it has been suggested that such results may be confounded by cognitive and functional status for which no information is available in claims data. Using survey data, we determined the magnitude of such bias and corrected the association between SSRI use and hip fractures accordingly. METHODS: We used the Medicare Current Beneficiary Survey to determine the association between SSRI use and 5 potential confounding factors not measured in Medicare claims data: body mass index, smoking, activities of daily living score, cognitive impairment, and Rosow-Breslau physical impairment scale. For 7126 participants aged > or =65 years, we estimated the association between SSRI use and these potential confounders. Combined with literature estimates of the associations between confounders and hip fractures, we were able to compute the extent of residual confounding bias caused by a failure to adjust for these factors. RESULTS: Comparing SSRI users with nonusers, there was considerable overestimation of an association with hip fractures if activities of daily living scores (+21.5% bias) or Rosow-Breslau impairment scales (+10.6%) are unmeasured in claims data. All 5 unmeasured confounders together resulted in net confounding of +9.6% (range: -0.3% to + 39%). After correction for this bias, the strength of association observed in claims data after bias correction (RR = 1.8; 95% CI = 1.5 to 2.1) was comparable to a recent clinical study (RR = 1.5; 0.6 to 3.8), but the claims data study achieved formal statistical significance due to its much large size (8239 vs. 288 hip fractures). CONCLUSIONS: Epidemiologic claims data studies tend to overestimate the relation between antidepressant use and hip fractures. However, after correcting for such bias, a significant association persists.

Aged↗
PubMed1990

Value of mammographic screening: assessment of studies and opinion.

The purpose of mammographic screening is to improve patient survival by detecting cancer at an earlier, more curable stage than is possible with physical examination. Three major studies have been used to assess the effect of mass screening on the survival rates and mortality for patients with breast cancer: the Breast Cancer Detection Demonstration Project, the Health Insurance Plan study, and the study conducted by the Swedish National Board of Health and Welfare. The author reviews these studies, describes statistical biases (lead time, length time, patient self-selection, and overdiagnosis) to be considered in study design and analysis, and discusses briefly risks versus benefits of mammography.

Bias↗
PubMed2004

Assessing risk-adjustment approaches under non-random selection.

Various approaches have been proposed to adjust for differences in enrollee risk in health plans. Because risk-selection strategies may have different effects on enrollment, we simulated three types of selection--dumping, skimming, and stinting. Concurrent diagnosis-based risk adjustment, and a hybrid using concurrent adjustment for about 8% of the cases and prospective adjustment for the rest, perform markedly better than prospective or demographic adjustments, both in terms of R2 and the extent to which plans experience unwarranted gains or losses. The simulation approach offers a valuable tool for analysts in assessing various risk-adjustment strategies under different selection situations.

Female↗
PubMed1999

Validity of a questionnaire survey: the role of non-response and incorrect answers.

Errors in questionnaire surveys are usually of one of two sources: non-responses or incorrect answers. The aim was to investigate the validity of a questionnaire survey and to estimate the respective bias of these answers. Of 9,283 subjects selected to receive a questionnaire by post, 3,949 (43%) responded, and, of these, 3,400 correctly reported their Swedish social security number. Answers in the questionnaire survey were given as proportions of the claims registered at local insurance offices. In the group of respondents who had correctly reported their social security number, the answers were compared individually with the registrations in dental insurance claims. In Sweden, these claims are labeled with the patient's social security number and it is thereby possible to make such comparisons. It was shown that errors were caused by non-response and also by respondents giving incorrect answers. Incorrect answers accounted for approximately one-third of the total bias. The remaining bias was caused by a non-response error. It is concluded that questionnaire studies have a bias caused by both non-response and incorrect answers and that together these can be substantial. Scientific reports that include questionnaire surveys must describe the procedure carefully. If possible, other sources of information should be considered.

Bias↗
PubMed2001

Impact of abciximab versus eptifibatide on length of hospital stay for PCI patients.

The purpose of this study is to compare the profile of percutaneous coronary intervention (PCI) patients who receive abciximab versus eptifibatide, as well as to compare the effect of abciximab versus eptifibatide on hospital length of stay. Retrospective data were obtained from HCIA's Clinical Pathways Database on 5,446 coronary angioplasty patients who were administered either abciximab or eptifibatide. Estimation was conducted via a two-stage sample selection model. In the first stage, a probit regression was employed to determine which factors were associated with a higher probability of being administered abciximab versus eptifibatide. In the second stage, a negative binomial model was used to estimate the impact of a wide range of factors (selection of GPIIb/IIIa, patient demographics, insurance provider, health conditions, admission information, and hospital characteristics) on total hospital length of stay, as well as on postprocedural length of stay. After controlling for high-risk indications and other sources of selection bias, results indicate that receipt of abciximab was associated with a significantly shorter length of total hospital stay (0.83 fewer days; P < 0.001) than receipt of eptifibatide. Additionally, receipt of abciximab was found to be associated with a significantly shorter postprocedural hospital length of stay (0.48 fewer days; P = 0.002) compared to receipt of eptifibatide. Results of this study indicate that PCI patients who are administered abciximab versus eptifibatide have a significantly shorter length of hospital stay (both total and postprocedural). This finding is important since hospital length of stay reflects the occurrence of complications and has been found to be directly related to the resources consumed during in-patient management of patients. Cathet Cardiovasc Intervent 2001;53:296-303.

Abciximab↗
PubMed2002

The use of expensive health technologies in the era of managed care: the remarkable case of neonatal intensive care.

UNLABELLED: The use of neonatal intensive care (NIC) continued to rise rapidly in the 1990s despite the concerns of observers about its cost effectiveness and its successes being mostly in facilities with high volume and capabilities. The objective of this study is to test the effects of insurance type, competition among hospitals, and market pressure from managed care plans on the supply and cost of NIC. The analysis uses logistic and linear models with techniques to avoid bias from (a) market area definitions based on actual patient flows and (b) self-selection of hospitals by patients with unmeasured risk of needing NIC. The data source contains all births in short-term hospitals in New Jersey during 1990 and 1994. Both the number of days and charges for NIC are reported. Key findings are that the decision of a hospital to offer NIC was associated with teaching status, the proportion of infants in the market area with documented high risk, and the market concentration of major competitors. The market share of managed care plans and the concentration of enrollment were not associated with either NIC being offered or with the standardized charges. Whether a particular patient was given to a NIC depended on patient risk factors and whether a NIC unit was present, but not on payer group. The results are consistent with the hypothesis that young insured parents (with the advice of their obstetricians) prefer hospitals with NIC and also are relatively profitable enrollees for health plans. IN CONCLUSION: using the results here and in other research, public and private policy makers may consider several ways to strengthen the incentives for health plans to contract for cost-effective birth-related services. The results also raise questions for a number of regulatory and payment policies and call for better public data on costs and outcomes for NIC.

Cost-Benefit Analysis↗
PubMed2004

Cancer prevention services and physician consensus in primary care group practices.

BACKGROUND: We conducted a randomized clinical trial of interventions to achieve physician consensus, practice changes, and patient activation designed to help primary care group practices enhance the delivery of cancer prevention and screening services. METHODS: In each of 42 primary care practices in 1991 to 1994, we studied approximately 60 patients per physician who were between the ages 53 and 64. Data sources included patient and physician questionnaires, medical record audits of consenting patients for evidence of 11 cancer prevention services during the previous 3 years, and telephone interviews with key practice personnel. RESULTS: None of the interventions was associated with significant changes in frequency of services or procedures received or provided. Increased frequencies of services overall and of specific activities were associated with HMO membership or insurance coverage for six screening procedures. Patient reports of clinic staff recommendations to have each of six screening procedures were specifically associated with higher frequencies of services (P = 0.001). CONCLUSIONS: Demonstration of intervention impact may have been limited because the rates of prevention services were significantly higher in this study than have been reported elsewhere. These results might be explained by selection biases inherent in studying patients with a regular provider, overall practice trends for changes in provision of the studied services, and the study methods.

Attitude of Health Personnel↗
PubMed2005

Health services research in the privacy age.

BACKGROUND: Strengthened regulations concerning privacy of health information are affecting large-scale health outcomes research. OBJECTIVE: To create a data collection system that would facilitate outcomes research, avoid selection bias, and fulfill obligations to protect privacy. DESIGN: We created a web-based system that uses touch-screen computer technology for longitudinal collection of data. The system provides access to information in deidentified form, enables it to be linked to health services and outcomes data, and allows patients to join a research registry project (RRP) and be placed on a prospective subject list (PSL). PARTICIPANTS, MEASUREMENTS, AND RESULTS: Pilot testing in 86 consecutive patients who were seen at a large, urban, university-based general medicine practice and had a mean age of 50 years showed that 81 patients had no difficulty, 5 had some difficulty, and none had considerable difficulty using the computer technology to complete a health survey. No patients refused to complete the survey and all patients completed the entire survey. Forty-seven (55%) joined the RRP and 42 of these 47 (89%) joined the PSL. RRP participants were less likely than RRP nonparticipants to be divorced or widowed (P=.03) and less likely to have hypertension (P=.03) but had no other significant differences in sociodemographic or clinical characteristics. PSL participants did not differ from PSL nonparticipants. CONCLUSIONS: The new system ensures privacy and appears to facilitate research recruitment and avoid selection bias.

Adult↗