A Practical ANOVA Approach for Uncertainty Analysis in Population-Based Disease Microsimulation Models

Objectives

To provide a practical approach for calculating uncertainty intervals and variance components associated with initial-condition and dynamic-equation parameters in computationally expensive population-based disease microsimulation models.

An Inner-City Asthma Disease Management Initiative

Objectives: The purpose of this study was to evaluate the effects of a recently implemented disease management programme [Asthma Control and Education Program (ACE)] on patient outcomes (clinical and functional) and on resource utilisation in socio-economically disadvantaged (and largely Hispanic) individuals with asthma treated at Hartford Hospital. Design and Setting: Using standardised measures (i.e. the Health Status Questionnaire [HSQ] and the Center for Epidemiologic Studies Depression Scale) and conducting serial assessments the investigators determined: (i) functional status at intake and follow-up; (ii) change in the level of illness severity over time; (iii) patientss’ acquisition of self-management skills; and (iv) the type and frequency of acute care services utilised pre- and post-enrolment in ACE. Patient Population:The study participants consisted of consenting individuals, aged 18 years or older, enrolled in ACE from 1 January 1997 to 30 September 1998. Each individual had a comprehensive intake interview (data collected included clinical and financial status) followed by 3 educational sessions. Results: While only 34.7% (n = 282) of the 813 patients referred from Hartford Hospital to physicians or emergency department services elected to participate in the programme, 60% of participants completed the educational sessions. 73% of these enrollees returned for the 3-month follow-up.On the HSQ, the mean Physical Composite Summary (PCS) scores increased from 33.3 ± 10.01 at baseline to 41.6 ± 11.48 at the 3-month follow up and 45.3 ± 10.30 at the 6-month follow-up. In an analysis using only those patients (n = 50) with HSQ scores at baseline and 3- and 6-month follow-ups, there were statistically significant increases in both the PCS and the Mental Composite Summary scores (p < 0.001).For the 68 patients with severity data at baseline, 3 months and 6 months there was a statistically significant improvement over time (p < 0.001). For example, 4.4% had severe disease at 6 months versus 69.1% at baseline. A subset of 73 patients for whom pre-ACE data were available realised a 37% reduction in emergency department use and a 52% reduction in in-patient visits. Conclusions: The evaluation of disease management programmes requires outcomes data. The results of this study of an asthma disease management programme indicate there was an improvement in overall functioning, illness severity, self-management, and utilisation of inpatient and emergency department services. Although a cause and effect relationship could not be assumed, the results suggest that the disease management model is an effective one for the studied population of inner-city patients, socioeconomically disadvantaged individuals previously identified as high utilisers of healthcare services and as having significant environmental exposures problematic for patients with asthma. As currently designed, however, this programme does not address the healthcare needs of the large number of referred patients who choose not to enrol or the enrollees (40%) who do not complete the education and follow-up sessions.     

Population-Based Disease Management in the German Statutory Health Insurance

Social healthcare systems in Europe must cope with aging populations and rising costs. For the German social healthcare system, which dates back to the 19th century, this problem is especially apparent, as soaring structural unemployment and the demographic transition of the population threaten the financial basis of the Statutory Health Insurance (SHI) [Gesetzliche Krankenversicherung]. In order to preserve free access to high-quality care and mandatory insurance for most of the population with affordable contributions, the traditional methods of healthcare delivery are challenged. As a result of its historic development, the system is tailored to acute care. Infectious diseases and accidents, however, have lost their relevance as main sources of mortality and morbidity of the population.Chronic diseases that can be influenced in their course by patient self-management and preventive measures dominate as causes of morbidity, mortality, and rising costs of healthcare. Since cost-containment measures can no longer stabilize cost development, structural reforms are strongly advocated. The implementation of a legal framework for disease management programs is the first of several structural reform measures implemented in the SHI.Diseases for which a legal framework has been approved include type 1 and type 2 diabetes mellitus, coronary artery disease, breast cancer, and asthma/chronic obstructive pulmonary disease. Quality requirements for the programs are high and include a central-accreditation process, evaluation in 3-year intervals by independent investigators, and specific quality management measures outlined for each disease. Major features of the programs include a population-based, patient-centric, and physician-based design. Since 2002, >1.6 million patients were enrolled in diabetes programs nationwide.Preliminary results point to positive effects of the programs on outcomes and process parameters, such as blood glucose and blood pressure readings or performed yearly eye examinations for patients with diabetes. Differences in the German and the US approach to disease management not only include a top-down versus a bottom-up approach; the German approach aims at secondary prevention regardless of risk state, co-morbidities, and possible cost savings, whereas in the US high-risk approaches are common. For the US, the German physician-based approach to disease management could be of interest in the evolving Medicare programs whereas German programs could become more effective drawing on US pay-for-quality experiences.Disease management, whether vendor or physician based, may not be the ultimate solution to all problems in the care of chronically ill patients, but it may facilitate change from a system traditionally focused on acute care to one focused on chronic care.     

A Community Approach to Respiratory Disease

The pulmonary retention of certain volatile compounds and particulate matter in cigarette smoke was studied in humans. A smoke-dosage apparatus delivered a standard puff which was inhaled and subsequently exhaled into cold traps. Acetaldehyde, isoprene, acetone, acetonitrile, toluene, particulate matter, and carbon monoxide were measured and compared with the amounts found in noninhaled smoke. A 86% to 99% retention was found for all compounds except carbon monoxide of which 54% was retained. These findings stress the importance of using methods which approximate actual smoking conditions when evaluating the biological effect of tobacco smoke.     

Major Components of an Asthma Disease Management Programme

In an effort to improve patient outcomes and reduce resource use and costs associated with asthma care, asthma disease management programmes have now gained momentum. If a programme is to be effective, the identification of goals and outcomes relevant to the target populations is essential. These may include strategies aimed at reducing the use of resources, improving patient symptom scores and quality-of-life measures, or normalising pulmonary function. Methods to measure such outcomes should be developed in the design phase of the programme.The best practice model for asthma care incorporates a multidisciplinary approach, using asthma care specialists, case managers, primary care physicians and nurse educators to target ‘high-risk’ asthmatics. The key interventions include incorporating clinical pathways developed from evidence-based guidelines, patient education and removal of obstacles to care and adherence. Assessment of outcomes and continuous efforts to improve quality are needed to make the programme cost effective.     

Asthma as a Model for Chronic Disease Management Programs

Chronic obstructive pulmonary disease (COPD) is a relatively new target for disease management programs; however, asthma has long been a focus for such programs, and can provide a template for respiratory disease management. A major difficulty when developing disease management programs in an area that has not previously been targeted is determining the outcomes that need to be monitored. In this area, experience in asthma management may provide direction for the management of other COPDs.Healthcare providers that manage patients with chronic respiratory diseases must use a variety of outcome measures to guide therapy. No single measure provides a complete picture of an individual’s perceived well-being and future risk of pulmonary decline. Therefore, clinicians must consider outcome measures that reflect both the short- and long-term morbidity associated with the disease process. These outcome measures include both objective measures of pulmonary function and quality-of-life assessments.Ideally, objective measures of pulmonary function would allow for direct determination of the rate of pulmonary decline. Inherent limitations mean that these measurements are instead used as a surrogate for disease control. The goal therefore is to reduce the impairment experienced by an individual and potentially slow the rate of decline in pulmonary function. The most commonly used measures of pulmonary function are pulmonary function tests, peak expiratory flows, and airway hyper-responsiveness. To use them effectively, clinicians must be aware of the information provided by these measures and the limitations with their use.Outcome measures related to quality of life provide information about a patient’s subjective experience and ability to function in daily life. It has been recognized that these measures are important to individuals with chronic diseases and that they provide clinicians with information about the disease process that cannot be determined using measures of pulmonary function. Such measures can be broadly grouped into healthcare utilization measures, symptom scores, and measures of activity limitation. These measures are essential components of long-term asthma management, but are subject to their own limitations.Measurements of pulmonary function and quality of life provide complementary information about respiratory disease processes. For example, asthma guidelines incorporate both types of measurements into current classification schemes to assess asthma impairment and risk of future morbidity. Further research is required to better understand the relationship between these outcome measures.     

Population-Based Assessment of Asthma Symptom Burden in Children

The Minneapolis and St. Paul Controlling Asthma in American Cities Project (CAACP) used a school-based symptom survey to inform community-based programming and provide an intermediate outcome measure of progress toward reducing the burden of asthma. In collaboration with the two school districts, the project mailed the Child Asthma Short Form, a validated health-related quality of life instrument to parents of children in grades K–8 every other school year from 2003 to 2007. The survey was mailed to a randomly selected sample in four languages (English, Spanish, Hmong, and Somali). The overall response rate was 47%, 41%, and 32% for years 1, 3, and 5, respectively. Two out of three children for whom surveys were completed were children of minority populations; more than 50% were eligible for free or reduced-price meals. The changes in scores from the first round (2003–2004) to the third round (2007–2008) were statistically significant for daytime symptom burden (p?<?0.05). Improvements were noted, but not statistically significant, for nighttime symptoms and functional limitations. Children of some racial/ethnic minority groups and children eligible for free or reduced-price meals had the highest symptom burden. Findings were used to guide CAACP’s program development and delivery to populations in greatest need. CAACP’s experience in Minneapolis and St. Paul demonstrates the feasibility of administering a symptom burden survey at low cost and in compliance with school system and institutional review board requirements to maintain confidentiality. The symptom-based survey may be a useful tool to track trends and changes in health disparities at a community and population level.     

Utilization and Financial Outcomes of an Asthma Disease Management Program Delivered to Medicaid Members

Background

Although various studies have reported the financial outcomes of disease management programs for commercial populations, few have addressed the outcomes for Medicaid recipients. McKesson Heath Solutions (MHS) disease management programs support clients whose members have serious chronic illnesses including asthma, diabetes, congestive heart failure, coronary artery disease, chronic obstructive pulmonary disease, and mental health conditions. This study describes financial outcomes of the MHS asthma disease management program by evaluating changes in health services utilization measures for Medicaid members who participated in the asthma disease management program.

Objective

To analyze and describe medical care utilization for asthma patients enrolled in a Medicaid managed care organization located in the eastern US.

Methods

Medicaid participants were identified and referred to the asthma program by the healthcare plan. Two comparison groups were used in the study to more reliably assess program impact. The first comparison group included members who were referred to the program, but who chose not to participate. The second group included members who were identified through medical claims data, but who were not contacted or referred to the program by the plan. All eligible participants with at least 30 days of program participation, and all non-participants with at least 30 days of effective plan enrollment in the pre- and post-program periods were included in the study.The utilization rates for the three groups were compared in the pre- and post-program periods. The effect of group membership on inpatient admissions (IP), emergency department (ED) visits, and hospital outpatient department/physician office (MD) visits was analyzed using Poisson regressions. The regression analyses controlled for baseline levels of utilization, demographics, and relative risk scores generated by D_xCG® software (manufactured by D_xCG® in Boston, Massachusetts, USA).

Results

While the MHS asthma disease management program has created positive financial outcomes for commercial populations, this study extends that scope to include a Medicaid population as well. 313 Medicaid participants experienced significant decreases in IP admissions and ED visits following program implementation. Participants also experienced decreased MD visits between the pre-program and program periods; however, their post-program MD visits were not reliably predicted by group membership after controlling for demographic differences and relative risk scores.

Conclusions

The experience of the MHS asthma disease management program demonstrates its efficacy and relevance to Medicaid populations. This study strongly suggests that a structured asthma program may create positive financial outcomes while promoting enhanced self-management through continued support, education, and patient involvement.

     

A Population-Based Study of Cardiovascular Disease Risk in Sexual-Minority Women

Objectives. We sought to determine if sexual-minority women were at greater risk for cardiovascular disease (CVD) than their heterosexual counterparts.Methods. We aggregated data from the 2001–2008 National Health and Nutrition Examination Surveys to examine differences in CVD risk between heterosexual and sexual-minority women by using the Framingham General CVD Risk Score to calculate a ratio of vascular and chronological age. We also examined differences in the prevalence of various CVD risk factors.Results. Sexual-minority women were more likely to be current or former smokers, to report a history of drug use, to report risky drinking, and to report a family history of CVD. On average, sexual-minority women were 13.9% (95% confidence interval [CI] = 8.5%, 19.3%) older in vascular terms than their chronological age, which was 5.7% (95% CI = 1.5%, 9.8%) greater than that of their heterosexual counterparts. Family history of CVD and history of drug use were unrelated to increased CVD risk, and this risk was not fully explained by either risky drinking or smoking.Conclusions. Sexual-minority women are at increased risk for CVD compared with heterosexual women.Cardiovascular disease (CVD) is the leading cause of death for women in the United States and has a mortality rate for women 10 times greater than that of breast cancer.1 Although there has been a significant reduction in CVD mortality rates in recent years, the decline in CVD deaths has been significantly smaller for women than for men.2 The leading modifiable risk factors for CVD include smoking, physical inactivity, obesity, elevated lipid levels, and diabetes.3 With the exception of smoking, women have a greater prevalence of these risk factors than men.2Subgroups of women may be at greater risk for CVD relative to all women. Sexual minority women (SMW; i.e., women who identify a sexual orientation other than heterosexual or who engage in same-sex sexual behavior) may be one such group because, in part, of increased prevalence of certain CVD risk factors. A growing line of research indicates that SMW are more likely to smoke are than heterosexual women.4,5 In a systematic review of 42 studies from 1987 to 2007, Lee et al. found that SMW were 1.5 to 2 times more likely to smoke than their heterosexual counterparts.6 Moreover, being overweight (body mass index [BMI; defined as weight in kilograms divided by the square of height in meters] = 25–29.9 kg/m²) or obese (BMI ≥ 30 kg/m²) may also contribute to increased CVD risk among SMW.3 Previous studies have found that SMW have a higher prevalence of being overweight or obese than their heterosexual counterparts.4,7–11 For instance, using the National Family Growth Survey, Boehmer et al. found that SMW (defined as lesbian-identified women) were more than twice as likely to be overweight or obese than heterosexual women.8 In addition, SMW have higher rates of heavy alcohol and drug use,12 which are both independent risk factors for CVD.13,14 With the increased prevalence of these CVD risk factors among SMW, there is reason to believe that disparities in CVD may exist for SMW.The recent Institute of Medicine report on the health of lesbian, gay, bisexual, and transgender people noted a paucity of research concerning CVD among sexual minorities in general.12 Of the few studies conducted, the majority have focused on increased risk of CVD among HIV-infected individuals and among transgender individuals who utilize masculinizing hormones. To date, only a few population-based studies have examined the relationship between sexual minority status and the prevalence of CVD among women. In a study of 4135 women participating in the 1999 Los Angeles County Health Survey, Diamant and Wold found that, even after they adjusted for demographic characteristics, BMI, and current smoking status, self-identified lesbian and bisexual women were significantly more likely to report a diagnosis of heart disease than were their heterosexual counterparts.15 Conversely, Cochran and Mays found no differences in self-reported heart disease between SMW and heterosexual women in the California Quality of Life Survey.16 Conron et al. also found no difference in self-reports of cardiovascular disease between SMW and their heterosexual counterparts when analyzing aggregated 2001–2008 data from the Massachusetts Behavioral Risk Factor Surveillance Survey; however, self-identified lesbians and bisexuals were more likely to report multiple risks for CVD.4 The reason for these contradictory results is unclear, but it may be the result of differences in age or the geographic distribution of the samples.The purpose of the current study was to compare the risk for CVD between SMW and heterosexual women by using national population-based health surveillance data. After pooling data from the National Health and Nutrition Examination Survey (NHANES) from 2001 to 2008, we calculated estimates of vascular age for a sample of heterosexual and sexual minority women by utilizing the multivariable Framingham General CVD risk score.17 Vascular age, which can be conceptualized as the age of a person’s heart and vascular system given his or her individual set of CVD risk factors, is a more useful metric than absolute CVD risk in younger to middle-aged populations because it provides an estimate of CVD risk relative to an individual’s chronological age.18 In the present study, we calculated the ratio of participants’ vascular and chronological age as a measure of CVD risk and compared it by sexual minority status. In addition, we compared differences in individual CVD predictor variables across sexual minority status to investigate the primary drivers of CVD risk in this population.     

Evaluation of an Asthma Disease Management Program in a Medicaid Population

In 2002, an asthma disease management program was initiated in Washington State in the US. The program was designed for clients of the state’s Medicaid program, which provides health coverage for qualified low-income state residents. In response to the escalating cost of healthcare and because of concerns about the quality of care, the Washington State Legislature mandated implementation of this disease management program as a pilot project to assist individuals to improve their health. Medicaid administrators used a carefully designed process to identify client needs and to obtain proposals for disease management programs.The asthma program seeks to narrow the gap between the standards of care and its practice. In particular, the program aims to provide patients with a richer understanding of asthma and how to control it. This is accomplished through disease education, symptom awareness and management, trigger avoidance, self-monitoring, and education on recommended medication strategies. The program is based on the US National Institutes of Health’s published guidelines on the optimal treatment of asthma.Enrollment of Medicaid clients into the asthma program began in April 2002. This article describes three approaches to evaluation of the first 3 years of the program: (i) 3 years of self-reported client data; (ii) an independent evaluation of the first year’s changes in utilization and quality of care; and (iii) an actuarial analysis of cost effectiveness. The first study used vendor-reported data collected during initial and follow-up assessments. The authors of this first study also reported the results of a satisfaction survey conducted on behalf of the vendor. The independent evaluation conducted by the University of Washington relied on medical record review and claims analysis, and reported statistical analysis of pre/post comparisons. The actuarial study also reported pre/post comparisons using an analysis of claims per member per month in periods before the program started and at 1 and 2 years of program operations.Clients were assessed according to several dimensions of health including self-management, symptoms, functional status, medication management, and trigger management. Numerous interventions were provided to study participants including access to round-the-clock telephone consultation with a registered nurse, self-care education, alerts sent to the primary provider, and symptom issue follow-up. The asthma disease management program outcomes provide evidence of initial success for those clients who completed the reassessment process. The results of the first 3 years of participation in the program indicate trends toward improved health status and client satisfaction with the program. Long-term evaluation will be necessary to determine if the program reduces costs and closes the quality chasm. If successful, this program could serve as a model for programs with similar clients and similar challenges.     

Management of Asthma

Asthma is a chronic inflammatory disorder of the airways. The worldwide prevalence of asthma has increased in recent decades. There is an approximately 20-fold variation (range 1.6% to 36.8%) in the prevalence of childhood asthma throughout the world. The highest prevalence rates are in the UK, Australia, New Zealand, the Republic of Ireland and Canada. The indirect costs of asthma, which include absence from school, lost productivity and premature death, are substantial.The goals of asthma therapy include controlling the disease and maintaining the well-being of the patient. Identification and avoidance of factors that precipitate asthma attacks are important in achieving satisfactory control of asthma. A stepped-care approach to drug therapy, in which anti-inflammatory therapy is the cornerstone, is recommended.Zafirlukast is a cysteinyl leukotriene type 1 receptor antagonist that causes bronchodilation and has anti-inflammatory properties. Oral zafirlukast 20mg twice daily was more effective than placebo in relieving symptoms, improving lung function, reducing requirements for as-needed β₂-agonists and preventing exacerbations in patients ≥12 years of age with mild to moderate asthma. Zafirlukast 20mg twice daily produced improvements in symptoms and reductions in as-needed β₂-agonist rescue medication similar to inhaled sodium cromoglycate in patients with asthma. As an alternative to inhaled corticosteroids, zafirlukast 20mg twice daily produced improvements in night-time wakenings, mornings with asthma and reductions in the use of β₂-agonist rescue medication in patients with mild to moderate asthma. However, beclomethasone dipropionate 200 to 250µg twice daily produced greater improvement than zafirlukast in all efficacy parameters and significantly greater improvements in morning peak expiratory flow rate, forced expiratory volume in 1 second and daytime symptoms than zafirlukast. In patients with asthma uncontrolled on low dosages of inhaled corticosteroids, the addition of oral zafirlukast 40 or 80mg twice daily was as effective as doubling the dose of the inhaled corticosteroid.The most common adverse events associated with zafirlukast in trials ≤20 weeks long were pharyngitis, headache and aggravation reactions, the incidence of which was similar to that in placebo recipients. Drug-drug interactions involving zafirlukast and aspirin, erythromycin, terfenadine, theophylline and warfarin have been described.Zafirlukast is indicated for the prophylactic treatment of chronic asthma. The drug is currently recognised in the US guidelines as an alternative to inhaled corticosteroids in patients aged ≥12 years with mild persistent asthma. As an adjunct to corticosteroids, the role of zafirlukast is still evolving, but it seems likely that patients with asthma of all severities may benefit from the drug.