Matthias Hunger

Official statistics and claims data records indicate non-response and recall bias within survey-based estimates of health care utilization in the older population

BackgroundThe validity of survey-based health care utilization estimates in the older population has been poorly researched. Owing to data protection legislation and a great number of different health care insurance providers, the assessment of recall and non-response bias is challenging to impossible in many countries. The objective of our study was to compare estimates from a population-based study in older German adults with external secondary data.MethodsWe used data from the German KORA-Age study, which included 4,127 people aged 65–94 years. Self-report questions covered the utilization of long-term care services, inpatient services, outpatient services, and pharmaceuticals. We calculated age- and sex-standardized mean utilization rates in each domain and compared them with the corresponding estimates derived from official statistics and independent statutory health insurance data.ResultsThe KORA-Age study underestimated the use of long-term care services (−52%), in-hospital days (−21%) and physician visits (−70%). In contrast, the assessment of drug consumption by postal self-report questionnaires yielded similar estimates to the analysis of insurance claims data (−9%).ConclusionSurvey estimates based on self-report tend to underestimate true health care utilization in the older population. Direct validation studies are needed to disentangle the impact of recall and non-response bias.

Quality of life several years after myocardial infarction: comparing the MONICA/KORA registry to the general population†

AIMS The aim of this study was to assess the impact of myocardial infarction (MI) on health-related quality of life (HRQL) in MI survivors measured by EuroQol (EQ-5D) and to compare it with the general population. METHODS AND RESULTS A follow-up study of all MI survivors included in the MONICA/KORA registry was performed. About 2950 (67.1%) patients responded. Moderate or severe problems were most frequent in EQ-5D dimension pain/discomfort (55.0%), anxiety/depression (29.2%), and mobility (27.9%). Mean EQ VAS score was 65.8 (SD 18.5). Main predictors of lower HRQL included older age, diabetes, increasing body mass index, current smoking, and experience of re-infarction. Type of revascularizational treatment showed no impact on HRQL. Compared with the general population, adjusted EQ VAS was 6.2 (95% confidence interval 3.4-8.9) points lower in 45-year-old MI patients converging with growing age up to the age of 80. With regard to HRQL dimensions, MI survivors had a significantly higher risk of incurring problems in the dimension pain/discomfort, usual activities, and especially in anxiety/depression which was more pronounced in younger age. Mobility was the single dimension, in which MI showed an inverse effect. CONCLUSION MI is combined with significant reduction in HRQL compared with the general population. The main impairments occur in the dimension pain/discomfort, usual activities, and particularly anxiety/depression. The relative impairment decreases with higher ages.

Multimorbidity and health-related quality of life in the older population: results from the German KORA-Age study

BackgroundMultimorbidity in the older population is well acknowledged to negatively affect health-related quality of life (HRQL). Several studies have examined the independent effects of single diseases; however, little research has focused on interaction between diseases. The purpose of this study was to assess the impact of six self-reported major conditions and their combinations on HRQL measured by the EQ-5D.MethodsThe EQ-5D was administered in the population-based KORA-Age study of 4,565 Germans aged 65 years or older. A generalised additive regression model was used to assess the effects of chronic conditions on HRQL and to account for the nonlinear associations with age and body mass index (BMI). Disease interactions were identified by a forward variable selection method.ResultsThe conditions with the greatest negative impact on the EQ-5D index were the history of a stroke (regression coefficient -11.3, p < 0.0001) and chronic bronchitis (regression coefficient -8.1, p < 0.0001). Patients with both diabetes and coronary disorders showed more impaired HRQL than could be expected from their separate effects (coefficient of interaction term -8.1, p < 0.0001). A synergistic effect on HRQL was also found for the combination of coronary disorders and stroke. The effect of BMI on the mean EQ-5D index was inverse U-shaped with a maximum at around 24.8 kg/m2.ConclusionsThere are important interactions between coronary problems, diabetes mellitus, and the history of a stroke that negatively affect HRQL in the older German population. Not only high but also low BMI is associated with impairments in health status.

Longitudinal beta regression models for analyzing health-related quality of life scores over time.

BackgroundHealth-related quality of life (HRQL) has become an increasingly important outcome parameter in clinical trials and epidemiological research. HRQL scores are typically bounded at both ends of the scale and often highly skewed. Several regression techniques have been proposed to model such data in cross-sectional studies, however, methods applicable in longitudinal research are less well researched. This study examined the use of beta regression models for analyzing longitudinal HRQL data using two empirical examples with distributional features typically encountered in practice.MethodsWe used SF-6D utility data from a German older age cohort study and stroke-specific HRQL data from a randomized controlled trial. We described the conceptual differences between mixed and marginal beta regression models and compared both models to the commonly used linear mixed model in terms of overall fit and predictive accuracy.ResultsAt any measurement time, the beta distribution fitted the SF-6D utility data and stroke-specific HRQL data better than the normal distribution. The mixed beta model showed better likelihood-based fit statistics than the linear mixed model and respected the boundedness of the outcome variable. However, it tended to underestimate the true mean at the upper part of the distribution. Adjusted group means from marginal beta model and linear mixed model were nearly identical but differences could be observed with respect to standard errors.ConclusionsUnderstanding the conceptual differences between mixed and marginal beta regression models is important for their proper use in the analysis of longitudinal HRQL data. Beta regression fits the typical distribution of HRQL data better than linear mixed models, however, if focus is on estimating group mean scores rather than making individual predictions, the two methods might not differ substantially.

Analysis of SF-6D Index Data: Is Beta Regression Appropriate?

BACKGROUND Preference-weighted index scores of health-related quality of life are commonly skewed to the left and bounded at one. Beta regression is used in various disciplines to address the specific features of bounded outcome variables such as heteroscedasticity, but has rarely been used in the context of health-related quality of life measures. We aimed to examine if beta regression is appropriate for analyzing the relationship between subject characteristics and SF-6D index scores. METHODS We used data from the population-based German KORA F4 study. Besides classical beta regression, we also fitted extended beta regression models by allowing a regression structure on the precision parameter. Regression coefficients and predictive accuracy of the models were compared to those from a linear regression model with model-based and robust standard errors. RESULTS The beta distribution fitted the empirical distribution of the SF-6D index better than the normal distribution. Extended beta regression performed best in terms of predictive accuracy but confidence intervals of the fit measures suggested that no model was superior to the others. Age had a significant negative effect on the precision parameter indicating higher variation of health utilities in older age groups. The observations reporting perfect health had a high influence on model results. CONCLUSIONS Beta regression, especially with precision covariates is a possible supplement to the methods currently used in the analysis of health utility data. In particular, it accounted for the boundedness and heteroscedasticity of the SF-6D index. A pitfall of the beta regression is that it does not work well in handling one-valued observations.

Does nurse-based case management for aged myocardial infarction patients improve risk factors, physical functioning and mental health? The KORINNA trial

Background Older patients with acute myocardial infarction (MI) are often lacking optimal support to continue rehabilitation after discharge from hospital. The objective of the study was to examine whether a home-based case management programme led by nurses can improve atherogenic risk factors, physical functioning, and mental health in the first year following discharge. Methods The KORINNA study is a randomized two-armed parallel group trial including 329 patients (aged 65–92 years) from the Augsburg Hospital in southern Germany. The intervention consisted of an individualized follow-up programme with a duration of 1 year, including home visits and telephone calls. The control group received usual care. Secondary outcome measures included clinical parameters (blood pressure, lipid parameters), functional status measures, cognitive status, depressive symptoms, and nutrition risk. Results At 1-year follow up, patients in the intervention group (n = 116) had significantly better low-density lipoprotein cholesterol levels (−8.4 mg/dl, 95% CI –16.4 to −0.4), hand grip strength (+2.53 kg, 95% CI 0.56 to 4.50), and SCREEN-II nutrition risk scores (+2.03, 95% CI 0.58 to 3.48) than patients in the control group (n = 136). The intervention group also had better mean scores with regard to self-reported disability, activities in daily living, and mental health, but differences were not always significant and meaningful. Conclusions The results of the KORINNA study indicate that nurse-based case management can improve blood lipid levels, functional status, and nutrition risk of aged patients with MI.

The impact of preoperative patient characteristics on health states after total hip replacement and related satisfaction thresholds: a cohort study

BackgroundThe aim of the study was to analyze the effect of preoperative patient characteristics on health outcomes 6 months after total hip replacement (THR), to support patients decision making in daily practice with predicted health states and satisfaction thresholds. By giving incremental effects for different patient subgroups, we support comparative effectiveness research (CER) on osteoarthritis interventions.MethodsIn 2012, 321 patients participated in health state evaluation before and 6 months after THR. Health-related quality of life (HRQoL) was measured with the EQ-5D questionnaire. Hip-specific pain, function, and mobility were measured with the WOMAC in a prospective observation of a cohort. The predictive capability of preoperative patient characteristics – classified according to socio-demographic factors, medical factors, and health state variables – for changes in health outcomes is tested by correlation analysis and multivariate linear regressions. Related satisfaction thresholds were calculated with the patient acceptable symptom state (PASS) concept.ResultsThe mean WOMAC and EQ-5D scores before operation were 52 and 60 respectively (0 worst, 100 best). At the 6-month follow-up, scores improved by 35 and 19 units. On average, patients reported satisfaction with the operation if postoperative (change) WOMAC scores were higher than 85 (32) and postoperative (change) EQ-5D scores were higher than 79 (14).ConclusionsChanges in WOMAC and EQ-5D scores can mainly be explained by preoperative scores. The lower the preoperative WOMAC or EQ-5D scores, the higher the change in the scores. Very good or very poor preoperative scores lower the probability of patient satisfaction with THR. Shared decision making using a personalized risk assessment approach provides predicted health states and satisfaction thresholds.

The Association Between Patient-Reported Self-Management Behavior, Intermediate Clinical Outcomes, and Mortality in Patients With Type 2 Diabetes: Results From the KORA-A Study

OBJECTIVE Little is known about the impact of diabetes self-management behavior (SMB) on long-term outcomes. We aimed to examine the association among patient-reported SMB, intermediate clinical outcomes, and mortality in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS Data were collected from 340 patients with type 2 diabetes of the KORA-A study (1997/1998) who were recruited from two previous population-based surveys (n = 161) and a myocardial infarction registry (n = 179) in southern Germany. Based on previous methodological work, a high level of SMB was defined as being compliant with at least four of six different self-care dimensions, comprising physical exercise, foot care, blood glucose self-monitoring, weight monitoring, having a diet plan, and keeping a diabetes diary. The vital status of the participants was observed until 2009. Multivariable linear, logistic, and Cox regression models were applied to assess the association with intermediate clinical outcomes at baseline and to predict mortality over the follow-up period, adjusted for sociodemographic, behavioral, and disease-related factors. RESULTS In the cross-sectional perspective, a high level of SMB was weakly associated with a lower glycated hemoglobin A1c level (−0.44% [−4.8 mmol/mol] [95% CI −0.88 to 0.00]), but not with low-density lipoprotein cholesterol, systolic blood pressure, or the presence of microalbuminuria, peripheral arterial disease, or polyneuropathy. During a mean follow-up time of 11.6 years, 189 patients died. SMB was a preventive factor for all-cause (hazard ratio 0.61 [95% CI 0.40–0.91]) and cardiovascular mortality (0.65 [95% CI 0.41–1.03]). CONCLUSIONS Although measuring SMB is difficult and the used operationalization might be limited, our results give some indication that a high level of SMB is associated with prolonged life expectancy in patients with type 2 diabetes and highlight the potential impact of the patients’ active contribution on the long-term trajectory of the disease. We assume that the used proxy for SMB is associated with unmeasured, but important, dimensions of health behavior.

The Economic Burden of Obesity in Germany: Results from the Population-Based KORA Studies

Objective: To estimate the excess costs of obese compared to normal-weight persons in Germany based on self-reported resource utilisation and work absence. Methods: Five cross sectional surveys of cohort studies in southern Germany were pooled resulting in 9,070 observations for 6,731 individuals (31-96 years). BMI was measured in the study centre. Self-reported health care utilisation and work absence was used to estimate direct and indirect costs for the year 2011 based on unit costs. Using regression analyses, adjusted costs for different BMI groups were calculated. Results: Overweight and obese people showed significantly higher odds of health care utilisation and productivity losses compared with normal-weight people in most categories. Total direct/indirect costs were significantly higher with increasing severity of obesity (pre-obese (1.05 (0.90-1.23) / 1.38 (1.11-1.71)), obesity level I (1.18 (1.00-1.39) / 1.33 (1.02-1.73)), obesity level II (1.46 (1.14-1.87) / 1.77 (1.18-2.65)) or level III (2.04 (1.40-2.97) / 1.99 (1.20-3.30)) compared to normal-weight participants. In particular, higher obesity classes were significantly associated with increased costs for medication, general practitioner utilisation and work absence. Conclusion: Our results show that overweight and obesity are associated with enormous societal direct and indirect costs in Germany. This supports the evidence from previous top-down studies, but provides important new information based on a large pooled data set and measured BMI.

Drug Costs in Prediabetes and Undetected Diabetes Compared With Diagnosed Diabetes and Normal Glucose Tolerance: Results From the Population-Based KORA Survey in Germany

Undetected diabetes and prediabetes are common (1–3). In decision analytic models of diabetes prevention and screening in particular, the differentiation in costs of detected, undetected, and prediabetic cases are important (4). To the best of our knowledge, no study has determined costs using population-based data with oral glucose tolerance test (OGTT)–based diabetes diagnosis. We used the population-based Cooperative Health Research in the Region of Augsburg (KORA) follow-up survey, conducted in 2006–2008 in southern Germany (2,3) ( n = 2,611, aged 40–82 years). By means of participants’ self report and an OGTT, we identified individuals with previously diagnosed diabetes ( n = 233, 57.9% male, mean age 67.8 ± 8.7), undetected diabetes ( n = 109, 56.9% male, mean age 65.3 ± 10.4), and prediabetes (i.e., impaired glucose tolerance and/or impaired fasting glucose) ( n = 489, 53.2% male, mean age 63.7 ± 10.4), and those with normal …