Measures Of Health Care Utilization Research Articles

The Long-term Impacts of Birth Weight and Respiratory Complications after a Preterm Birth

Background: Infant respiratory distress syndrome (RDS) and bronchopulmonary dysplasia (BPD) remain important respiratory complications of preterm births. This study aims at establishing the incidence and impact of respiratory complications and extreme low birth weight (ELBW) on the healthcare utilization of a population of preterm infants. Methods: Retrospective cohort study using administrative healthcare databases of the province of Quebec (Canada). The main outcome measures of healthcare utilization, hospital admissions, hospital mortality and use of prescription drugs were studied in 55 033 subjects born prematurely with or without respiratory complications such as BPD or RDS between 1999 and 2009. Results: Preterm infants with BPD and RDS had significantly higher hospital readmissions per person-year. This trend persisted for the entire duration of the 10-year follow-up. Diagnoses of childhood asthma, attention deficit hyperactivity disorder and cerebral palsy were more frequent in BPD subjects, but were not influenced by birth weight. Extreme low birth weight carried odds ratio of 38.0 [33.5, 43.2] and 3.5 [3.2, 3.9] respectively for the occurrence of BPD and RDS, and was associated with greater mortality, longer hospital stay and more medical visits per person-year. Except for anxiolytics and sedatives, bronchopulmonary dysplasia subjects were not more likely to have been prescribed neurological and psychiatric medications. Conclusions: Birth weight is a major determinant in the occurrence of respiratory complications following a preterm birth. The impacts of BPD and extreme low birth weight following a preterm birth have lasting consequences on respiratory health and healthcare utilization.

Cardiac diagnoses, procedures, and healthcare utilisation in inpatients with Ellis–van Creveld syndrome

Ellis-van Creveld syndrome is a rare condition associated with a very high incidence of congenital malformations of the heart. Prior reports have suggested increased morbidity and mortality following surgery for congenital malformations of the heart in patients with Ellis-van Creveld syndrome. The Pediatric Health Information System database, an administrative database containing data from 43 free-standing paediatric hospitals in North America, was queried to search for patients with the diagnostic code for Ellis-van Creveld syndrome between 2004 and 2011. Those patients who underwent cardiac procedures were compared with those who did not with respect to measures of healthcare utilisation. A total of 138 admissions occurred in 93 patients with Ellis-van Creveld syndrome during the study period. Of these, 74% had an underlying diagnosis of congenital malformations of the heart. Half of the patients in the sample underwent a cardiac surgical or interventional catheterisation procedure. Patients who underwent a cardiac procedure had a longer hospital length of stay, higher incidence of intensive care unit admission, and higher total and per day hospital charges than patients who did not undergo cardiac surgery during admission. In a large group of inpatients with Ellis-van Creveld syndrome, the prevalence of congenital malformations of the heart was similar to that reported in prior studies. Cardiac surgical and interventional procedures appear to drive a substantial portion of healthcare utilisation in these patients.

Mental Health and High‐Cost Health Care Utilization: New Evidence from Axis II Disorders

To analyze the associations between Axis II (A2) disorders and two measures of health care utilization with relatively high cost: emergency department (ED) episodes and hospital admissions. Wave I (2001/2002) and Wave II (2004/2005) of the National Longitudinal Survey on Alcohol and Related Conditions (NESARC). A national probability sample of adults. Gender-stratified regression analysis adjusted for a range of covariates associated with health care utilization. The target population of the NESARC is the civilian noninstitutionalized population aged 18 years and older residing in the United States. The cumulative survey response rate is 70.2 percent with a response rate of 81 percent (N=43,093) in Wave I and 86.7 percent (N=34,653) in Wave II. Both men and women with A2 disorders are at elevated risk for ED episodes and hospital admissions. Associations are robust after adjusting for a rich set of confounding factors, including Axis I (clinical) psychiatric disorders. We find evidence of a dose-response relationship, while antisocial and borderline disorders exhibit the strongest associations with both measures of health care utilization. This study provides the first published estimates of the associations between A2 disorders and high-cost health care utilization in a large, nationally representative survey. The findings underscore the potential implications of these disorders on health care expenditures.

Can we trust measures of healthcare utilization from household surveys?

BackgroundThe research community relies heavily on measures of healthcare utilization from household surveys to understand health seeking choices and to evaluate interventions in developing countries. Such measures are known to suffer from recall problems but there is limited evidence of whether the method of data collection affects evaluation findings. We compared the results of a randomized trial of free healthcare using utilization data from two sources.MethodsData are from a study in Ghana, in which 2,194 households containing 2,592 children under 5 y old were randomized into a prepayment scheme providing free primary and some referral care, or to a control group whose families paid user fees for healthcare. Data on morbidity and health seeking behaviour were collected using a standard household survey administered at endline and a pictorial diary given to households over a six month period, collected at monthly intervals.ResultsSelf-reported measures of morbidity and healthcare utilization were substantially lower in the household survey than the pictorial diary when the recall period was over a month. Introducing free healthcare had a positive effect on primary care visits based on the pictorial diary and a non-significant negative effect according to the household survey. Using any clinic visit in the past month as the outcome, the difference in the effect of free care between the two data collection methods was 3.6 percentage points (p = 0.078).ConclusionsThe findings raise methodological concerns about measures of healthcare utilization from household surveys, particularly in the evaluation of health financing interventions.

Advancing Comparative Studies of Patterns of Care and Economic Outcomes in Cancer: Challenges and Opportunities

Advancing Comparative Studies of Patterns of Care and Economic Outcomes in Cancer: Challenges and Opportunities

Healthcare Utilization in Medical Intensive Care Unit Survivors with Alcohol Withdrawal

Rehospitalization is an important and costly outcome that occurs commonly in several diseases encountered in the medical intensive care unit (ICU). Although alcohol use disorders are present in 40% of ICU survivors and alcohol withdrawal is the most common alcohol-related reason for admission to an ICU, rates and predictors of rehospitalization have not been previously reported in this population. We conducted a retrospective cohort study of medical ICU survivors with a primary or secondary discharge diagnosis of alcohol withdrawal using 2 administrative databases. The primary outcome was time to rehospitalization or death. Secondary outcomes included time to first emergency department or urgent care clinic visit in the subset of ICU survivors who were not rehospitalized. Cox proportional hazard models were adjusted for age, gender, race, homelessness, smoking, and payer source. Of 1,178 patients discharged from the medical ICU over the study period, 468 (40%) were readmitted to the hospital and 54 (4%) died within 1 year. Schizophrenia (hazard ratio 2.23, 95% CI 1.57, 3.34, p < 0.001), anxiety disorder (hazard ratio 2.04, 95% CI 1.30, 3.32, p < 0.01), depression (hazard ratio 1.62, 95% CI 1.05, 2.40, p = 0.03), and Deyo comorbidity score ≥3 (hazard ratio 1.43, 95% CI 1.09, 1.89, p = 0.01) were significant predictors of time to death or first rehospitalization. Bipolar disorder was associated with time to first emergency department or urgent care clinic visit (hazard ratio 2.03, 95% CI 1.24, 3.62, p < 0.01) in the 656 patients who were alive and not rehospitalized within 1 year. The presence of a psychiatric comorbidity is a significant predictor of multiple measures of unplanned healthcare utilization in medical ICU survivors with a primary or secondary discharge diagnosis of alcohol withdrawal. This finding highlights the potential importance of targeting longitudinal multidisciplinary care to patients with a dual diagnosis.

Biologic disease-modifying anti-rheumatic drugs and the risk of non-vertebral osteoporotic fractures in patients with rheumatoid arthritis aged 50 years and over

Prevention of bone mineral density loss in rheumatoid arthritis (RA) has been associated with use of biologic disease-modifying anti-rheumatic drugs (DMARDs). However, in this study, we could not demonstrate a reduction in the risk of non-vertebral fractures. Additional research is required to clarify the impact of biologic DMARDs on fracture risk in RA. Small studies have suggested biologic DMARDs preserve bone mineral density at 6-12 months. Our objective was to determine the association between biologic DMARD use and the risk of non-vertebral osteoporotic fractures in RA subjects aged ≥50 years. A nested case-control study was conducted using Quebec physician billing and hospital discharge data. RA subjects were identified from International Classification of Disease-9/10 codes in billing and hospitalisation data and followed from cohort entry until the earliest of non-vertebral osteoporotic fracture, death, or end of study period. Controls were matched to cases (4:1 ratio) on age, sex, and date of cohort entry. Biologic DMARD exposure was defined as being on treatment for ≥180 days pre-fracture (index). Conditional logistic regression was used, adjusting for indicators of RA severity, comorbidity, drugs influencing fracture risk, and measures of health care utilisation. Over the study period, 1,515 cases were identified (6,023 controls). The most frequent fracture site was hip/femur (42.3%). In total, 172 subjects (49 cases and 123 controls) were exposed to biologic DMARDs. The median duration of exposure was 735 (interquartile range (IQR), 564) and 645 (IQR, 903) days in cases and controls, respectively. We were unable to demonstrate an association between biologic DMARDs and fracture risk (odds ratio, 1.03; 95% confidence interval, 0.42-2.53). RA duration significantly increased the fracture risk. Despite the positive impact of biologic DMARDs on bone remodelling observed in small studies, we were unable to demonstrate a reduction in the risk of non-vertebral osteoporotic fractures in older adults with RA.

Continuity, Coordination, and Transitions of Care for Patients with Serious and Advanced Illness: A Systematic Review of Interventions

Continuity, coordination, and transitions of care are key to high-quality medical care for patients with serious and advanced illness. We conducted a systematic review to evaluate the impact of interventions targeting these areas in this population. We searched PubMed, CINAHL, PsycINFO, Cochrane, and DARE from 2000 through 2011. We included prospective controlled studies targeting continuity, coordination, and transitions for patients with advanced illness that reported patient centered outcomes. Of 13,014 citations, 23 studies met inclusion criteria. Two investigators extracted and checked data on population, interventions, methods, outcomes, and methodological quality. Four of the six studies evaluating patient satisfaction (67%) and four of the six studies evaluating caregiver satisfaction (67%) showed statistically significant improvements in these outcomes in the intervention compared to the control group. Only three of the nine studies (33%) measuring quality of life and five of the 16 (31%) measuring health care utilization showed improvement. Results were similar across different types of interventions. Many studies were limited by methodologic issues such as use of measurement tools not developed for patients with advanced disease and small sample size. Interventions and outcomes were too heterogeneous for meta-analysis. We found moderate evidence that interventions targeting continuity, coordination, and transitions in patients with advanced and serious illness improve patient and caregiver satisfaction, but low evidence for other outcomes. Further research is needed on how to target these domains for outcomes such as health care utilization.

Health care utilization and psychosocial factors in pediatric noncardiac chest pain.

This study investigated factors related to health care utilization (HCU) among patients presenting to pediatric cardiologists with symptoms of chest pain later diagnosed as noncardiac chest pain (NCCP). Participants included 67 children and adolescents diagnosed with NCCP and their parent. Measures of HCU, pain severity, and child self-report and parent self-report of anxiety and depression were collected at the cardiologist's office. The child's sex was examined as a moderator of HCU. Pain severity and maternal and child depression were significant contributors to the variance in child HCU. The relationship between depression and HCU was moderated by the child's sex, with boys higher in levels of maternal or child depression reporting greater HCU. Psychological factors are related to HCU for children with NCCP, with depression positively associated with HCU. The child's sex plays an important role in depression and HCU. Family-focused psychological screening of pediatric patients with NCCP may aid in identifying families who may benefit from referrals for psychological assessment and treatment.

Psychiatric pharmacogenomics predicts health resource utilization of outpatients with anxiety and depression

Antidepressants are among the most widely prescribed medications, yet only 35–45% of patients achieve remission following an initial antidepressant trial. The financial burden of treatment failures in direct treatment costs, disability claims, decreased productivity, and missed work may, in part, derive from a mismatch between optimal and actual prescribed medications. The present 1 year blinded and retrospective study evaluated eight direct or indirect health care utilization measures for 96 patients with a DSM-IV-TR diagnosis of depressive or anxiety disorder. The eight measures were evaluated in relation to an interpretive pharmacogenomic test and reporting system, designed to predict antidepressant responses based on DNA variations in cytochrome P450 genes (CYP2D6, CYP2C19, CYP2C9 and CYP1A2), the serotonin transporter gene (SLC6A4) and the serotonin 2A receptor gene (5HTR2A). All subjects had been prescribed at least one of 26 commonly prescribed antidepressant or antipsychotic medications. Subjects whose medication regimen included a medication identified by the gene-based interpretive report as most problematic for that patient and are in the ‘red bin' (medication status of ‘use with caution and frequent monitoring'), had 69% more total health care visits, 67% more general medical visits, greater than three-fold more medical absence days, and greater than four-fold more disability claims than subjects taking drugs categorized by the report as in the green bin (‘use as directed') or yellow bin (‘use with caution'). There were no correlations between the number of medications taken and any of the eight healthcare utilization measures. These results demonstrate that retrospective psychiatric pharmacogenomic testing can identify past inappropriate medication selection, which led to increased healthcare utilization and cost.

Vaccines for preventing influenza in people with asthma.

Influenza vaccination is recommended for asthmatic patients in many countries as observational studies have shown that influenza infection can be associated with asthma exacerbations. However, influenza vaccination has the potential to cause wheezing and adversely affect pulmonary function. While an overview concluded that there was no clear benefit of influenza vaccination in patients with asthma, this conclusion was not based on a systematic search of the literature. The objective of this review was to assess the efficacy and safety of influenza vaccination in children and adults with asthma. We searched the Cochrane Airways Group trials register and reviewed reference lists of articles. The latest search was carried out in November 2012. We included randomised trials of influenza vaccination in children (over two years of age) and adults with asthma. We excluded studies involving people with chronic obstructive pulmonary disease. Inclusion criteria and assessment of trial quality were applied by two review authors independently. Data extraction was done by two review authors independently. Study authors were contacted for missing information. Nine trials were included in the first published version of this review, and nine further trials have been included in four updates. The included studies cover a wide diversity of people, settings and types of influenza vaccination, and we pooled data from the studies that employed similar vaccines. PROTECTIVE EFFECTS OF INACTIVATED INFLUENZA VACCINE DURING THE INFLUENZA SEASON: A single parallel-group trial, involving 696 children, was able to assess the protective effects of influenza vaccination. There was no significant reduction in the number, duration or severity of influenza-related asthma exacerbations. There was no difference in the forced expiratory volume in one second (FEV) although children who had been vaccinated had better symptom scores during influenza-positive weeks. Two parallel-group trials in adults did not contribute data to these outcomes due to very low levels of confirmed influenza infection. ADVERSE EFFECTS OF INACTIVATED INFLUENZA VACCINE IN THE FIRST TWO WEEKS FOLLOWING VACCINATION: Two cross-over trials involving 1526 adults and 712 children (over three years old) with asthma compared inactivated trivalent split-virus influenza vaccine with a placebo injection. These trials excluded any clinically important increase in asthma exacerbations in the two weeks following influenza vaccination (risk difference 0.014; 95% confidence interval -0.010 to 0.037). However, there was significant heterogeneity between the findings of two trials involving 1104 adults in terms of asthma exacerbations in the first three days after vaccination with split-virus or surface-antigen inactivated vaccines. There was no significant difference in measures of healthcare utilisation, days off school/symptom-free days, mean lung function or medication usage.EFFECTS OF LIVE ATTENUATED (INTRANASAL) INFLUENZA VACCINATION: There were no significant differences found in exacerbations or measures of lung function following live attenuated cold recombinant vaccine versus placebo in two small studies on 17 adults and 48 children. There were no significant differences in asthma exacerbations found for the comparison live attenuated vaccine (intranasal) versus trivalent inactivated vaccine (intramuscular) in one study on 2229 children (over six years of age). Uncertainty remains about the degree of protection that vaccination affords against asthma exacerbations that are related to influenza infection. Evidence from more recently published randomised trials of inactivated split-virus influenza vaccination indicates that there is no significant increase in asthma exacerbations immediately after vaccination in adults or children over three years of age. We were unable to address concerns regarding possible increased wheezing and hospital admissions in infants given live intranasal vaccination.

Patterns of Illness Explaining the Associations between Posttraumatic Stress Disorder and the Use of CT

To examine the relationship between posttraumatic stress disorder (PTSD) and computed tomography (CT) utilization and to determine whether there were patterns of comorbid illness that could explain the relationship. The study was approved by the University of Iowa Institutional Review Board and the Iowa City Veterans Affairs Medical Center Research and Development Committee. By using a retrospective cohort design, a national sample of new veteran enrollees aged 18-35 years was studied. Associations were examined between the presence of PTSD, receipt of at least one and multiple CT scans, comorbid medical conditions (eg, abdominal pain, headaches), and measures of health care utilization (eg, primary care, emergency room, and mental health visits) and the daily probability of the receipt of at least one CT scan before and after a diagnosis of PTSD. Analyses included sequential multivariable generalized linear mixed models to examine the independent relationship between PTSD and CT scan utilization. Among the full cohort, 13.0% (10 018 of 76 812) received at least one CT scan. PTSD was identified in 21.1% (16 182 of 76 812) of the cohort, and 22.9% (3711 of 16 182) of veterans with PTSD received at least one CT scan as compared with 10.4% (6307 of 60 630) of veterans without PTSD (P < .0001). In sequential modeling, comorbid factors explaining the relationship between CT scans and PTSD were traumatic brain injury (odds ratio, 3.54; P < .0001), abdominal pain (odds ratio, 4.01; P < .0001), and headaches (odds ratio, 3.07; P < .0001). Associations were also strong for high levels of emergency room (odds ratio, 2.73; P < .0001) and primary care (odds ratio, 2.38; P < .0001) utilization. The daily chance of receiving a CT scan was seven times higher prior to the recognition of PTSD (daily chance, 0.007 before vs 0.001 after; P < .0001). Young veterans with PTSD are receiving more CT scans compared with those without PTSD; the daily probability of receiving CT scans is higher prior to recognition of PTSD. http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13121593/-/DC1.

Health policy and horizontal inequities of health-care utilization in Australia: 1983–2005

We used five National Health Surveys (NHSs) in order to measure horizontal inequity (equal health care for equal need) in health-care utilization in Australia over five time points from 1983 to 2005. The direct standardization method was used to estimate the horizontal inequity indices for six measures of health-care utilization. The results suggest that the distributions of General Practitioner (GP) services and any physician visits in Australia were generally pro-poor, whereas the distributions of specialist visits, dentist visits and any ambulatory visits were pro-rich. The computed indices demonstrate that the introduction of Medicare in 1984 had a pro-poor effect on the utilization of GPs, any physician visits and any ambulatory visits. In contrast, the implementation of Private Health Insurance (PHI) policies over the period 1997 to 2000 had a pro-rich effect on the distribution of health-care utilization in recent years, but this finding is based on the assumption that PHI policies affected health-care consumption in the long term.

Healthcare utilization in patients with Parkinson's disease: A population-based analysis

PurposeTo investigate factors associated with healthcare utilization and prescription drug use for Parkinson's disease (PD) patients and matched controls. MethodsA retrospective matched-group design was adopted using administrative data from Manitoba, Canada. PD cases (N = 1469) were identified from diagnoses in hospital records and physician billing claims and matched to controls (N = 2938) on age, sex, and region of residence. Sixteen measures of healthcare utilization were examined over a six-year period using generalized linear models. ResultsPD cases had greater healthcare utilization than controls for almost all investigated services, with the exception of visits to non-neurological specialists and hospital use for non-mental disorder diagnoses. For controls, utilization of all forms of healthcare increased with age; for PD cases the relationship was weak, except for specialist visits, where an inverse relationship was observed. A rural region of residence was associated with a lower rate of seeing a specialist or any medical doctor, with a higher rate of hospitalization than for urban cases or controls. Comorbidity was strongly associated with healthcare use for both groups. Over the six-year study period significant differences in the trend were observed for mental disorder hospitalizations, hospital days, and physician visits. ConclusionsFactors associated with healthcare utilization in PD patients differ from those without PD. This information may help to identify and optimize healthcare services and associated costs for PD patients.

Asthma outcomes: Healthcare utilization and costs

Measures of healthcare utilization and indirect impact of asthma morbidity are used to assess clinical interventions and estimate cost. National Institutes of Health institutes and other federal agencies convened an expert group to propose standardized measurement, collection, analysis, and reporting of healthcare utilization and cost outcomes in future asthma studies. We used comprehensive literature reviews and expert opinion to compile a list of asthma healthcare utilization outcomes that we classified as core (required in future studies), supplemental (used according to study aims and standardized), and emerging (requiring validation and standardization). We also have identified methodology to assign cost to these outcomes. This work was discussed at an National Institutes of Health-organized workshop in March 2010 and finalized in September 2011. We identified 3 ways to promote comparability across clinical trials for measures of healthcare utilization, resource use, and cost: (1) specify the study perspective (patient, clinician, payer, and society); (2) standardize the measurement period (ideally 12 months); and (3) use standard units to measure healthcare utilization and other asthma-related events. Large clinical trials and observational studies should collect and report detailed information on healthcare utilization, intervention resources, and indirect impact of asthma, so that costs can be calculated and cost-effectiveness analyses can be conducted across several studies. Additional research is needed to develop standard, validated survey instruments for collection of provider-reported and participant-reported data regarding asthma-related health care.

Modeling hospital length of stay by Coxian phase‐type regression with heterogeneity

Hospital length of stay (LOS) is an important measure of healthcare utilization and is generally positively skewed and heterogeneous. We fit a Coxian phase-type distribution to LOS and identify the hidden states of the underlying latent homogeneous Markov model. We demonstrate that selecting an appropriate number of phases and a regression model for hazard rates can account for some heterogeneity in LOS. Reversible jump MCMC method enables us to dynamically uncover the hidden stochastic Markov structure. A classification method is used to assign patients to different LOS groups. The methodology is illustrated with application to hospital admissions for acute myocardial infarction in the 2003 Nationwide Inpatient Sample from the Healthcare Utilization Project.

Assessing the association between receipt of dental care, diabetes control measures and health care utilization

The literature contains few studies regarding the relationships between receipt of regular dental care and medical outcomes for people with type 2 diabetes. The authors compared hemoglobin A(1c) (HbA(1c)) levels (< 7 percent versus < 7 percent), low-density lipoprotein cholesterol levels (< 100 milligrams/deciliter versus ≥ 100 mg/dL) and diabetes-specific hospital admissions and emergency department (ED) visits (one or more visits versus no visits) in 493 people with type 2 diabetes who received regular dental care (≥ two prophylactic visits, periodontal treatment visits or both during a 12-month period) with measures in 493 people with type 2 diabetes who did not receive any dental care. The authors matched patients, all of whom had private medical and dental insurance benefits during the study period, with regard to age, sex and previous utilization of ED visits and hospital admissions, and they followed them for three years. The authors analyzed the data by using multiple logistic regression, which showed that receipt of regular dental care was associated with lower diabetes-specific ED utilization (odds ratio [OR] = 0.61, 95 percent confidence interval [CI] = 0.40-0.92) and hospital admissions (OR = 0.61, 95 percent CI, 0.39-0.95) after they adjusted for age, sex, previous hospital admissions, previous ED utilization, race, baseline HbA(1c) values, Charlson comorbidity index score, body mass index status, periodontal risk status and primary care utilization. The authors found no significant association between receipt of dental care and control of HbA(1c) levels. The study results show an association between regular receipt of dental care and reduced diabetes-specific medical care utilization (that is, ED visits and hospital admissions). Although the results of this study could not show causality, they suggest that receipt of dental care may reduce diabetes-specific health care utilization. Prospective studies are needed to better understand the relationship of receipt of dental care with diabetes control and health care utilization measures.

Uninsurance Among Nonelderly Adults With and Without Frequent Mental and Physical Distress in the United States

This research describes uninsurance rates over time among nonelderly adults in the United States with or without frequent physical and mental distress and provides estimates of uninsurance by frequent mental distress status and sociodemographic characteristics nationally and by state. Data from the 1993 through 2009 Behavioral Risk Factor Surveillance System, a telephone survey that uses random-digit dialing, were used to examine the prevalence of uninsurance among nearly 3 million respondents by self-report of frequent physical and frequent mental distress and sociodemographic characteristics, response year, and state of residence. After adjustment for sociodemographic characteristics, uninsurance among adults aged 18 to 64 years was markedly higher among those with frequent mental distress only (22.6%) and those with both frequent mental and frequent physical distress (21.8%) than among those with frequent physical distress only (17.7%). The prevalence of uninsurance did not differ markedly between those with only frequent mental distress and those with both frequent mental distress and frequent physical distress. The prevalence of uninsurance among those with frequent mental distress only and those with neither frequent mental distress nor frequent physical distress increased significantly over time. Uninsurance rates among nonelderly adults with frequent mental distress were disproportionately high. The results of this analysis can be used as baseline data to assess whether implementation of the Affordable Care Act is accompanied by changes in health care access, utilization, and self-reported measures of health, particularly among those with mental illness.

The Fixed-Effects Zero-Inflated Poisson Model with an Application to Health Care Utilization

Response variables that are scored as counts and that present a large number of zeros often arise in quantitative health care analysis. We define a zero-inflated Poisson model with fixed-effects in both of its equations to identify respondent and health-related characteristics associated with health care demand. This is a new model that is proposed to model count measures of health care utilization and account for the panel structure of the data. Parameter estimation is achieved by conditional maximum likelihood. An application of the new model is implemented using micro level data from the 2004-2006 Survey of Health, Ageing and Retirement in Europe (SHARE), and compared to existing panel data models for count data. Results show that separately controlling for whether outcomes are zero or positive in one of the two years does make a difference for counts with a larger number of zeros.

Modelling bivariate count distributions with finite mixture models: application to health care demand of married couples

Count measures of health care utilization are often correlated with other measures of utilization. In addition, utilization measures display a high proportion of zero observations. This article attempts to accommodate both data features in one model, with an application to medical care usage of husbands and wives. A bivariate count representation is used to model dependence between husbands’ and wives’ utilizations, and a finite mixture specification accommodates the problem of excess zeros. Results show that married couples are characterized by two distinct subpopulations according to the intensity of utilization of the wife.