Body Mass Index, Weight Change and Death in an Older Hypertensive Population: The SHEP Study Grant W Somes Stephen B Kritchevsky Marco Pahor Ronald I Shorr William B Applegate University of Tennessee Health Science Center, Memphis, TN

Background: Static Measures of Weight and Mortality In older populations, most studies show that low BMI is associated with increased mortality risk Fewer studies have shown that high BMI is associated with increased mortality risk The relationship with low BMI is attenuated in those with long-term weight stability, non-smokers, and those without weight related health conditions (Diehr et al., 1999; Calle et al., 1999).

Background: Dynamic Measures of Weight and Mortality On a population-level, there is a general tendency for adults to lose weight after age 60. The dynamics of this change may be intimately related to health status. In clinical settings, acute weight loss (>5%/year) is associated with increased mortality. Most previous studies in older populations have had only two weights, one of which is recalled from over a decade previously. There is little data on older populations, looking at the importance of short-term weight change and mortality risk

Study Questions: In older adults... What is the relationship between baseline BMI and mortality? Outside of a clinical setting is weight change associated with mortality? What are the simultaneous effects of static and dynamic measures of weight on mortality?

Systolic Hypertension in the Elderly Program (SHEP) Randomized clinical trial of 4736 (isolated systolic) hypertensives, age 60 and older, comparing drug treatment with placebo. Primary endpoint was stroke (fatal or non-fatal). Vital status known for nearly 100% of enrolled subjects. (n=455 deaths) Average duration of follow-up of 4.5 years.

Present Study Inclusion Criteria –> 3 weight values –>1 year follow-up beyond 3rd weight value Exclusion Criteria –Missing data related to BMI calculation at baseline (randomization visit). –Missing data related to covariates (eg. Gender, smoking, diabetes, prevalent CHD etc) 4485/4736 subjects were included 351 (7.83%) deaths

Methods BMI represents the BMI recorded at randomization visit (kg/m 2 ). Weight measured quarterly, and at other SHEP visits. Weight change is the average annualized weight change based on the regression of weight on time from baseline until one year before last measurement (death, loss to follow-up, or end of study). Other baseline variables are gender, age (divided at 70), current smoking status, and risks (previous heart attack, stroke or diabetes)

Analytic Strategy The primary outcome was all cause mortality. BMI and Weight Change were divided into quintiles Logistic regression was used to related mortality risk to weight change and baseline BMI compared to participants at lowest risk (23.6 to 28.0 BMI and -0.7 to 0.5 kg/year Weight Change) Covariates –Age –Gender –Baseline smoking status –“Risk” »Prevalent CVD »Diabetes

Distribution of Risk Factors and Mortality in SHEP (n= 4485 )

Distribution of time to event in SHEP

Baseline BMI and Mortality

Weight Change and Mortality

BMI, Weight Change and Death 1 year (n= 351)

BMI, Weight Change and Death 2 years (n=281)

Weight Change and Death, Baseline BMI > 31.1

Weight Change and Death, Baseline BMI < 23.6

Weight Change in BMI Groups BMI 31.1

Weight Change and Mortality by smoking status

Weight Change and Mortality by risk group

Weight Change and Cancer (n=135) or CVD (n=148) mortality

Baseline BMI and Cancer (n=135) or CVD (n=148) mortality

Multivariate Model

Discussion Weight loss of more than 0.7 kg/year was associated with high mortality risk--even in persons with high BMI. Weight gain of more than 0.5 kg/year was associated with high mortality risk--even in persons with low BMI. Findings consistent with 1-year and 2-year lag. Therefore observed relationship between weight change and mortality less likely to be ascribed to terminal illness. Our findings consistent across major causes of death.

Conclusions Limitations: –Setting: Clinical trial in Isolated Systolic Hypertension –Involuntary v. voluntary weight change Dynamic weight measures are a more important predictor of mortality than static weight measures. Weight stability regardless of BMI is associated low mortality in older adults.