Effect of different distributional assumption of random parameters in the mixed logit model on willingness-to-pay values

Understanding consumers’ willingness-to-pay (WTP) value is vital for rational valuation of consumers’ benefit. Stated preference techniques such as Choice Experiment (CE) have been widely used to account for WTP value and one of the popular model specifications is the Mixed Logit (MXL) model. In the MXL model, it is essential to assume the types of distribution of random parameters. The specification of MXL models with different distributional assumptions of random parameters has been explored by many researchers. Nevertheless, the effect of different distributional assumptions of random parameters on goodness-of-fit, the significance of the coefficients and WTP values has not been studied adequately particularly in the context of Malaysia. In the present work, the analysis is carried out in this regard based on visitors’ preferences for tourist facilities at Tasik Kenyir, Malaysia. A number of MXL models were attempted with different distributional assumptions of random parameters; normal, log-normal, triangular and uniform. The results suggested that, in all MXL models, the goodness-of-fit statistics, the significance of the attribute coefficients and WTP values were quite comparable, except for the log-normal distribution. The methodological implications concern the importance of developing several MXL models with different distributional assumptions as well as the recommendation for policy makers to improve the facilities at the lake

Low income, community poverty and risk of end stage renal disease

BACKGROUND: The risk of end stage renal disease (ESRD) is increased among individuals with low income and in low income communities. However, few studies have examined the relation of both individual and community socioeconomic status (SES) with incident ESRD. METHODS: Among 23,314 U.S. adults in the population-based Reasons for Geographic and Racial Differences in Stroke study, we assessed participant differences across geospatially-linked categories of county poverty [outlier poverty, extremely high poverty, very high poverty, high poverty, neither (reference), high affluence and outlier affluence]. Multivariable Cox proportional hazards models were used to examine associations of annual household income and geospatially-linked county poverty measures with incident ESRD, while accounting for death as a competing event using the Fine and Gray method. RESULTS: There were 158 ESRD cases during follow-up. Incident ESRD rates were 178.8 per 100,000 person-years (105 py) in high poverty outlier counties and were 76.3 /105 py in affluent outlier counties, p trend = 0.06. In unadjusted competing risk models, persons residing in high poverty outlier counties had higher incidence of ESRD (which was not statistically significant) when compared to those persons residing in counties with neither high poverty nor affluence [hazard ratio (HR) 1.54, 95% Confidence Interval (CI) 0.75-3.20]. This association was markedly attenuated following adjustment for socio-demographic factors (age, sex, race, education, and income); HR 0.96, 95% CI 0.46-2.00. However, in the same adjusted model, income was independently associated with risk of ESRD [HR 3.75, 95% CI 1.62-8.64, comparing the < 20,000 income group to the > 75,000 group]. There were no statistically significant associations of county measures of poverty with incident ESRD, and no evidence of effect modification. CONCLUSIONS: In contrast to annual family income, geospatially-linked measures of county poverty have little relation with risk of ESRD. Efforts to mitigate socioeconomic disparities in kidney disease may be best appropriated at the individual level

Weight-modification trials in older adults: what should the outcome measure be?

BACKGROUND: Overweight older adults are often counseled to lose weight, even though there is little evidence of excess mortality in that age group. Overweight and underweight may be more associated with health status than with mortality, but few clinical trials of any kind have been based on maximizing years of healthy life (YHL), as opposed to years of life (YOL). OBJECTIVE: This paper examines the relationship of body mass index (BMI) to both YHL and YOL. Results were used to determine whether clinical trials of weight-modification based on improving YHL would be more powerful than studies based on survival. DESIGN: We used data from a cohort of 4,878 non-smoking men and women aged 65–100 at baseline (mean age 73) and followed 7 years. We estimated mean YHL and YOL in four categories of BMI: underweight, normal, overweight, and obese. RESULTS: Subjects averaged 6.3 YOL and 4.6 YHL of a possible 7 years. Both measures were higher for women and whites. For men, none of the BMI groups was significantly different from the normal group on either YOL or YHL. For women, the obese had significantly lower YHL (but not YOL) than the normals, and the underweight had significantly lower YOL and YHL. The overweight group was not significantly different from the normal group on either measure. CONCLUSIONS: Clinical trials of weight loss interventions for obese older women would require fewer participants if YHL rather than YOL was the outcome measure. Interventions for obese men or for the merely overweight are not likely to achieve differences in either YOL or YHL. Evaluations of interventions for the underweight (which would presumably address the causes of their low weight) may be conducted efficiently using either outcome measure

Association between English Proficiency and Kidney Disease Knowledge and Communication Quality among Patients with ESKD

KEY POINTS: In one hospital-based safety-net dialysis unit, only one half of patients with ESKD knew their cause of kidney failure, which did not differ by English proficiency status. Patients with limited English proficiency (versus English-proficient patients) reported poorer communication with the dialysis care team (less listening, fewer clear explanations, less time spent). We highlight the need for tailored, patient-centered communication between limited English-proficient patients and dialysis care team members. BACKGROUND: ESKD is a chronic health condition for which communication between health care teams and patients is important to guide patient self-management activities. Yet, little is known about the quality of communication among patients with ESKD and their care team members. We examined the influence of patient's limited English proficiency (LEP) status on communication experiences at one dialysis center. METHODS: A survey was administered to adults receiving ESKD care at a dialysis unit within a public health care delivery system between July 2022 and February 2023, to ascertain kidney disease knowledge and perceptions of communication quality with the dialysis care team. Multivariable logistic and ordinal logistic regression models adjusted for age and sex were used to determine associations between LEP status and CKD knowledge. RESULTS: Among 93 eligible patients, 88.2% (n=82) completed the survey. Approximately 37.8% (n=31) had LEP, mean age was 58.8 years, 68.3% were men, mean dialysis vintage was 3.9 years, and 25% had a positive depression screen (LEP 30%; English-proficient 22%). A higher proportion of English-proficient patients screened positive for limited health literacy compared to those with LEP (74.5% versus 38.7%, P = 0.002). Overall, knowledge of assigned cause of ESKD (53.4%) and CKD/transplant knowledge (57.3%) was suboptimal. After adjustment, LEP status was not significantly associated with knowing the correct cause of kidney failure (odds ratio, 0.49; 95% confidence interval, 0.19 to 1.27) but was significantly associated with having a higher score on a CKD/transplant knowledge scale (odds ratio, 3.99; 95% confidence interval, 1.66 to 9.58). Patients with LEP reported poorer communication quality with dialysis providers and staff (less listening, fewer clear explanations, less time spent with patients) compared with English-proficient patients, although differences were not statistically significant. CONCLUSIONS: Overall communication between patients with ESKD and members of the dialysis care team was suboptimal, regardless of English proficiency. Interventions to enhance communication for ESKD patients are needed

Urinary Tubular Injury Biomarkers Are Associated With ESRD and Death in the REGARDS Study.

IntroductionUrinary neutrophil gelatinase-associated lipocalin (uNGAL) and urinary kidney injury molecule-1 (uKIM-1) are established markers of subclinical acute kidney injury. In persons with reduced estimated glomerular filtration rate (eGFR) and albuminuria who are at high risk for end-stage renal disease (ESRD) and death, the associations of these urinary markers with incident ESRD or death is an area of active investigation.MethodsAmong 1472 black and white participants from the REasons for Geographic and Racial Differences in Stroke (REGARDS) study with eGFR ≤60 ml/min per 1.73 m2 (Chronic Kidney Disease Epidemiology Collaboration [CKD-EPI] cystatin, 2012) and albumin-to-creatinine ratio (ACR) ≥30 mg/g, we evaluated the associations of baseline uNGAL and uKIM-1 with progression to ESRD and all-cause death. Cox models were sequentially adjusted for urinary creatinine, traditional risk factors, C-reactive protein, ACR, and eGFR.ResultsThere were 257 ESRD events and 819 deaths over a median follow-up of 5.7 and 6.5 years, respectively. In demographic adjusted models, higher levels of uNGAL were associated with increased risk of ESRD and death, but these associations were attenuated in fully adjusted models including baseline eGFR for both ESRD (hazard ratio [HR] = 1.06 per doubling, 95% confidence interval [CI] 0.98-1.14) and death (HR = 1.04, 95% CI = 1.00-1.08). Higher levels of uKIM-1 were associated with increased risk of ESRD and death in demographic-adjusted models, and although attenuated in fully adjusted models, remained statistically significant for both ESRD (HR = 1.24 per doubling, 95% CI = 1.08-1.42) and death (HR = 1.10, 95% CI =1.03-1.19).ConclusionIn this cohort of high-risk patients with baseline eGFR ≤60 ml/min per 1.73 m2 and albuminuria, renal tubular injury is associated with higher mortality and progression to ESRD. Further studies are necessary to investigate the mechanism underlying this increased risk

Dealing with attributes non-attendance in a discrete choice experiment on valuation of tourist facilities attribute in Kenyir Lake, Malaysia

Accounting for ignored attributes, or attribute non-attendance (ANA), in discrete choice experiment (DCE) is believed to produce more reliable willingness to pay (WTP) estimates. However, there is evidence that respondents who claimed to have ignored some attributes may simply have assigned them lesser importance. To explore this issue in the context of tourism research, a new follow-up question is used to investigate whether the respondents have ignored certain attributes or just assigned the attribute as of lesser importance when responding. Three different mixed logit (MXL) models were estimated and compared. Results generally indicate that some respondents do indeed ignore certain attributes, and some of them put less emphasis on certain attributes when making decisions. Comparison of the different MXL models reveals different WTP estimates, suggesting the importance of considering an appropriate method to deal with ANA