Impact of alternative approaches to assess outlying and influential observations on health care costs

The distributions of medical costs are often skewed to the right because small numbers of patients use large amounts of health care resources. Using data from a study of colon cancer costs, we show, by example, the impact and magnitude of outliers and influential observations on health care costs and compared the effects of statistical costing methods for addressing the disproportionate influence of outliers and influential observations. We used data from a retrospective cohort study of 3,842 elderly veterans with colon cancer who were enrolled in and used health care from, both the Department of Veterans Affairs and Medicare in 1999–2004. After calculating the average colon cancer episode cost and distribution for the full cohort, we used box-plot methods, Winsorization, DFBETAs, and Cook's distance to identify and assess or adjust the outlying and/or influential observations. The number of observations identified as outlying and/or influential ranged from 13 when the predicted DFBETA measurement was greater than 0.15 and the observation was a qualified box-plot outlier to 384 cases using the Winsorization method at the 5th and 95th percentiles. Average costs of colon cancer episodes using these methods were similar. The method of choice from the results of this particular analysis can be conditionally based on whether the purpose is to control only for influential observations or to simultaneously control for outliers and influential observations. Understanding how estimates could change with each approach is important in assessing the impact of a particular method on the results

A System for Interactive Assessment and Management in Palliative Care

The availability of psychometrically sound and clinically relevant screening, diagnosis, and outcome evaluation tools is essential to high-quality palliative care assessment and management. Such data will enable us to improve patient evaluations, prognoses, and treatment selections, and to increase patient satisfaction and quality of life. To accomplish these goals, medical care needs more precise, efficient, and comprehensive tools for data acquisition, analysis, interpretation, and management. We describe a system for interactive assessment and management in palliative care (SIAM-PC), which is patient centered, model driven, database derived, evidence based, and technology assisted. The SIAM-PC is designed to reliably measure the multiple dimensions of patients’ needs for palliative care, and then to provide information to clinicians, patients, and the patients’ families to achieve optimal patient care, while improving our capacity for doing palliative care research. This system is innovative in its application of the state-of-the-science approaches, such as item response theory and computerized adaptive testing, to many of the significant clinical problems related to palliative care

Total daily energy expenditure in black and white, lean and obese South African women.

Background/Objectives:In South Africa (SA), the prevalence of obesity in women is 56%, with black women being most at risk (62%). Studies in the United States have demonstrated ethnic differences in resting (REE) and total daily energy expenditure (TDEE) between African American (AA) and their white counterparts. We investigated whether differences in EE exist in black and white SA women, explaining, in part, the ethnic obesity prevalence differences.Subjects/Methods:We measured REE, TDEE and physical activity EE (PAEE) in lean (BMI 30 kg m(-2)) SA women (N=44, 30+/-6 year). REE, TDEE, PAEE and total awake EE were measured during a 21 h stay in a respiration chamber.Results:Black and white subjects within obese and lean groups were not significantly different for age, mass, BMI and % body fat. However, fat-free mass (kg FFM) was consistently lower in the black women (P<0.01) in both weight groups. After adjusting EE measurements for differences in FFM, REE was not significantly different for either body weight or ethnicity, although 24 h TDEE (kJ) was significantly greater in the obese women (P<0.01) and white women (P<0.05). Total awake non-PAEE was not significantly different for either groups, while total awake time was only significantly lower for the lean groups (P<0.01). Total PAEE (kJ min(-1)) was significantly lower in the lean (P<0.001) and black groups (P<0.01).Conclusions:In this sample of matched, lean and obese, black and white SA women, differences in TDEE were largely explained by ethnic differences in PAEE, and were not as a result of ethnic differences in REE.European Journal of Clinical Nutrition advance online publication, 13 February 2008; doi:10.1038/ejcn.2008.8

Vitamin D Levels are Associated with Liver Disease Severity in Patients with Cirrhosis

Vitamin D deficiency is common in advanced liver disease but its clinical significance remains controversial. The aim of this study was to examine the correlation of 25-hydryoxyvitamin D levels with liver disease severity and calcium levels in adults with cirrhosis. This cross-sectional study included 180 adults with cirrhosis enrolled in a clinical cohort study at a single university hospital. The mean age was 58.8 (±9.2) years, and cirrhosis was attributed to alcohol use in 27.2%, hepatitis C in 35.0%, non-alcoholic steatohepatitis in 27.2%, and both alcohol and hepatitis C in 10.6%. The median model for end-stage liver disease-sodium (MELD-Na) score was 12.0 (interquartile range 9.0–16.0), and mean serum albumin levels were 3.4 (±0.7) gm/dl. Median serum 25-hydroxyvitamin D levels were 28.0 (interquartile range 20–38) ng/mL, with 16 patients (8.9%) having levels <12 ng/ml and 43 (23.9%) with 25(OH)D levels <20 ng/ml. No correlation was noted between levels of 25-hydroxyvitamin D and albumin-corrected calcium in the total group and in groups stratified by vitamin D supplementation. In contrast, both serum albumin (r = 0.32; P < 0.001) and MELD-Na scores were significantly correlated with 25-hydroxyvitamin D levels (r = –0.29; P < 0.001). Correlations between 25-hydroxyvitamin D levels and serum albumin (r = −0.39; P < 0.001) and MELD-Na scores did not change substantially after excluding 67 patients receiving vitamin D supplementation (r = −0.33; P = 0.009). In conclusion, total 25-hydroxyvitamin D levels correlate inversely with liver disease severity in adults with cirrhosis

Under-reporting of dietary energy intake in five populations of the African diaspora.

Studies on the role of diet in the development of chronic diseases often rely on self-report surveys of dietary intake. Unfortunately, many validity studies have demonstrated that self-reported dietary intake is subject to systematic under-reporting, although the vast majority of such studies have been conducted in industrialised countries. The aim of the present study was to investigate whether or not systematic reporting error exists among the individuals of African ancestry (n 324) in five countries distributed across the Human Development Index (HDI) scale, a UN statistic devised to rank countries on non-income factors plus economic indicators. Using two 24 h dietary recalls to assess energy intake and the doubly labelled water method to assess total energy expenditure, we calculated the difference between these two values ((self-report - expenditure/expenditure) × 100) to identify under-reporting of habitual energy intake in selected communities in Ghana, South Africa, Seychelles, Jamaica and the USA. Under-reporting of habitual energy intake was observed in all the five countries. The South African cohort exhibited the highest mean under-reporting ( - 52·1% of energy) compared with the cohorts of Ghana ( - 22·5%), Jamaica ( - 17·9%), Seychelles ( - 25·0%) and the USA ( - 18·5%). BMI was the most consistent predictor of under-reporting compared with other predictors. In conclusion, there is substantial under-reporting of dietary energy intake in populations across the whole range of the HDI, and this systematic reporting error increases according to the BMI of an individual

Elevated hypertension risk for African-origin populations in biracial societies : Modeling the Epidemiologic Transition Study.

OBJECTIVES: Blood pressures in persons of African descent exceed those of other racial/ethnic groups in the United States. Whether this trait is attributable to the genetic factors in African-origin populations, or a result of inadequately measured environmental exposures, such as racial discrimination, is not known. To study this question, we conducted a multisite comparative study of communities in the African diaspora, drawn from metropolitan Chicago, Kingston, Jamaica, rural Ghana, Cape Town, South Africa, and the Seychelles. METHODS: At each site, 500 participants between the age of 25 and 49 years, with approximately equal sex balance, were enrolled for a longitudinal study of energy expenditure and weight gain. In this study, we describe the patterns of blood pressure and hypertension observed at baseline among the sites. RESULTS: Mean SBP and DBP were very similar in the United States and South Africa in both men and women, although among women, the prevalence of hypertension was higher in the United States (24 vs. 17%, respectively). After adjustment for multiple covariates, relative to participants in the United States, SBP was significantly higher among the South Africans by 9.7 mmHg (P &lt; 0.05) and significantly lower for each of the other sites: for example, Jamaica: -7.9 mmHg (P = 0.06), Ghana: -12.8 mmHg (P &lt; 0.01) and Seychelles: -11.1 mmHg (P = 0.01). CONCLUSION: These data are consistent with prior findings of a blood pressure gradient in societies of the African diaspora and confirm that African-origin populations with lower social status in multiracial societies, such as the United States and South Africa, experience more hypertension than anticipated based on anthropometric and measurable socioeconomic risk factors

Moderate-vigorous physical activity and health-related quality of life among Hispanic/Latino adults in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL).

BackgroundPhysical activity is a modifiable healthy behavior that has been shown to positively influence health-related quality of life. However, research examining the link between physical activity and health-related quality of life among Hispanic/Latino adults is limited and inconsistent. The purpose of this study is to assess whether accelerometer-measured moderate-vigorous physical activity (MVPA) is associated with self-reported (a) mental health-related quality of life, and (b) physical health-related quality of life among diverse Hispanic/Latino adults in the US.MethodsCross-sectional data from 12,379 adults ages 18-74 years in 2008-2011, who participated in HCHS/SOL and had complete data were analyzed using complex survey design methods. Accelerometer data were categorized into no MVPA, low, moderate, and high MVPA. Health-related quality of life was assessed with the Short-Form 12 and we used the mental and physical component subscales where higher scores indicate better health-related quality of life. Multivariate linear regression models were used to derive adjusted means with 95% confidence intervals and linear trends.ResultsWe observed no significant linear trend between accelerometer-measured MVPA and mental health-related quality of life (ptrend = 0.73). There was a significant positive association between MVPA and physical health-related quality of life (ptrend &lt; 0.001) where higher MVPA corresponded with higher scores in physical health-related quality of life. The adjusted means were 46.67 (44.85-48.48) for no MVPA, 49.33 (49.03-49.63) for low MVPA, 50.61 (50.09-51.13) for moderate MVPA, and 51.36 (50.86-51.86) for high MVPA.ConclusionsAmong diverse Hispanic/Latino adults in the US, accelerometer-measured MVPA was associated with physical health-related quality of life, but not mental health-related quality of life. Future interventions should evaluate if increases in MVPA lead to improvements in health-related quality of life

Examining the BMI-mortality relationship using fractional polynomials

<p>Abstract</p> <p>Background</p> <p>Many previous studies estimating the relationship between body mass index (BMI) and mortality impose assumptions regarding the functional form for BMI and result in conflicting findings. This study investigated a flexible data driven modelling approach to determine the nonlinear and asymmetric functional form for BMI used to examine the relationship between mortality and obesity. This approach was then compared against other commonly used regression models.</p> <p>Methods</p> <p>This study used data from the National Health Interview Survey, between 1997 and 2000. Respondents were linked to the National Death Index with mortality follow-up through 2005. We estimated 5-year all-cause mortality for adults over age 18 using the logistic regression model adjusting for BMI, age and smoking status. All analyses were stratified by sex. The multivariable fractional polynomials (MFP) procedure was employed to determine the best fitting functional form for BMI and evaluated against the model that includes linear and quadratic terms for BMI and the model that groups BMI into standard weight status categories using a deviance difference test. Estimated BMI-mortality curves across models were then compared graphically.</p> <p>Results</p> <p>The best fitting adjustment model contained the powers -1 and -2 for BMI. The relationship between 5-year mortality and BMI when estimated using the MFP approach exhibited a J-shaped pattern for women and a U-shaped pattern for men. A deviance difference test showed a statistically significant improvement in model fit compared to other BMI functions. We found important differences between the MFP model and other commonly used models with regard to the shape and nadir of the BMI-mortality curve and mortality estimates.</p> <p>Conclusions</p> <p>The MFP approach provides a robust alternative to categorization or conventional linear-quadratic models for BMI, which limit the number of curve shapes. The approach is potentially useful in estimating the relationship between the full spectrum of BMI values and other health outcomes, or costs.</p

Statin and Aspirin Use Among Hispanic and Latino Adults at High Cardiovascular Risk: Findings From the Hispanic Community Health Study/Study of Latinos

BACKGROUND: Despite variations in the prevalence of cardiovascular disease and related risk factors among US Hispanic/Latino adults of diverse backgrounds, there is little information on whether disparities exist in the use of medications for the primary and secondary prevention of cardiovascular disease. We examined the prevalence of statin and aspirin use among diverse US Hispanic/Latino adults at high cardiovascular risk. METHODS AND RESULTS: A multicenter population-based study, the Hispanic Community Health Study/Study Of Latinos, included a total of 16 415 participants of Mexican, Puerto Rican, Cuban, Dominican, South American, and Central American backgrounds who were aged 18 to 74 years and enrolled between March 2008 and June 2011. Our analyses were limited to 4139 participants considered to be at high cardiovascular risk. Age-adjusted prevalence of statin and aspirin use was 25% and 44%, respectively, overall but varied by Hispanic/Latino background among those at high cardiovascular risk; statin use was significantly higher (P<0.001) among adults of Puerto Rican (33%) and Dominican (28%) backgrounds compared with adults of other backgrounds (Mexican, 24%; Cuban, 22%; Central American, 20%; South American, 22%). There was no difference in aspirin use. After adjusting for health insurance coverage, the difference in prevalence of statin use was substantially reduced among participants with a Puerto Rican background, from an odds ratio of 1.73 (95% CI 1.30-2.31) to 1.30 (95% CI 0.97-1.75), and with a Dominican background, from an odds ratio of 1.45 (95% CI 1.04-2.02) to 1.07 (95% CI 0.75-1.52), in comparison to their counterparts. CONCLUSIONS: Among Hispanic/Latino adults of diverse backgrounds, statin use was more prevalent among adults with Puerto Rican and Dominican backgrounds at high cardiovascular risk. These differences in statin use were explained, in part, by differences in insurance coverage. These findings have important implications for the prevention of disparities in cardiovascular outcomes within the growing US Hispanic/Latino population

A cardiovascular educational intervention for primary care professionals in Spain: positive impact in a quasi-experimental study

Background Routine general practice data collection can help identify patients at risk of cardiovascular disease. Aim To determine whether a training programme for primary care professionals improves the recording of cardiovascular disease risk factors in electronic health records. Design and setting A quasi-experimental study without random assignment of professionals. This was an educational intervention study, consisting of an online-classroom 1-year training programme, and carried out in the Valencian community in Spain. Method The prevalence rates of recording of cardiovascular factors (recorded every 6 months over a 4-year period) were compared between intervention and control group. Clinical relevance was calculated by absolute risk reduction (ARR), relative risk reduction (RRR), and number of patients needed-to-attend (NNA), to avoid under-recording, with their 95% confidence intervals (CIs). Linear regression models were used for each of the variables. Results Of the 941 professionals initially registered, 78.1% completed the programme. The ARR ranged from 1.87% (95% CI = 1.79 to 1.94) in the diagnosis of diabetes to 15.27% (95% CI = 15.14 to 15.40) in the recording of basal blood glucose. The NNA ranged from 7 in blood pressure, cholesterol, and blood glucose recording to 54 in the diagnosis of diabetes. The RRR ranged from 26.7% in the diagnosis of diabetes to 177.1% in the recording of the Systematic Coronary Risk Evaluation (SCORE). The rates of change were greater in the intervention group and the differences were significant for recording of cholesterol (P<0.001), basal blood glucose (P<0.001), smoking (P<0.001), alcohol (P<0.001), microalbuminuria (P = 0.001), abdominal circumference (P<0.001), and SCORE (P<0.001). Conclusion The education programme had a beneficial effect at the end of the follow-up that was significant and clinically relevant.We are grateful to Conselleria de Sanidad for allowing access to the ABUCASIS system and Antonio Fernandez who provided technical support during the study period