Weight Gain: Predictor of Heart Failure Hospitalization
Abstract & Commentary
By Andrew Boyle, MBBS, PhD, Assistant Professor of Medicine, Interventional Cardiology, University of California, San Francisco, CADr. Boyle reports no financial relationships relevant to this field of study.
Source: Chaudhry SI, et al. Patterns of weight change preceding hospitalization for heart failure. Circulation. 2007;116:1549-1554.
Weight gain has long been used as a marker of fluid retention in heart failure patients. It is a cheap, simple test that can be performed daily in patients' homes. Heart failure hospital admissions are a considerable strain on health budgets and, therefore, a number of strategies aimed at preventing recurrent hospitalizations are being implemented. Increasingly, strategies for remote monitoring of patients who remain at home are being developed, and heart failure is an obvious target where these interventions may prevent hospitalization and reduce health care costs. However, studies delineating the pattern of weight gain in ambulatory heart failure patients using remote monitoring have been lacking.
Chaudhry and colleagues studied patients enrolled in a home-based remote heart failure monitoring program that consists of daily weight transmitted via telephone line to a central location that is monitored by trained cardiac nurses. From over 10,000 patients, 393 had at least one heart failure admission over the 18-month follow-up period. They were able to match 134 patients who had heart failure hospital admissions with 134 patients who did not with age, gender, weight at enrollment, NYHA class, and month of enrollment. Mean patient age was 74 years; 55% were female, and the vast majority of patients were in NYHA class III heart failure. They showed that patients started to increase weight by around 1 pound approximately 30 days before admission due to heart failure. This was maintained until 2 weeks before admission, when patients started to gain more weight, and this pattern accelerated in the week prior to admission. They showed that the amount of weight gained in this cohort predicted the likelihood of hospital admission for heart failure. Compared to those whose weight changed < 2 pounds, the odds ratio (OR) for heart failure admission for a weight gain of 2-5 lbs was 2.77, for weight gain 5-10 lbs OR was 4.46, and for > 10 lbs weight gain OR was 7.65. From the same cohort, they chose a group of patients who were admitted to hospital for non-heart failure reasons, and matched them with a control cohort. There was no weight gain prior to non-heart failure admissions. Chaudhry and colleagues concluded that increases in weight in moderate-to-severe heart failure patients are associated with subsequent admission for heart failure and occur at least one week before admission.
Although weight gain has long been a surrogate for fluid retention in heart failure, the current study is important for several reasons. Firstly, they have demonstrated that a simple, safe test can be performed in patients' homes and remotely recorded accurately enough to allow prediction of a clinical event. This lends validity to the ongoing search for remote monitoring parameters for heart failure patients to prevent readmission. Secondly, it shows that fluid retention precedes admission to hospital by quite a long time, with weight gain being seen in the week prior to admission, but may be seen as much as 30 days prior to admission. This delineates a window of opportunity wherein interventions may be initiated to prevent hospitalization (eg, increase diuretic dose), but this remains to be studied in prospective clinical trials.
The study is limited by the small number of patients included from the overall cohort. This was due to problems matching them with controls, or by withdrawal due to early hospitalization in the initial 30 days, which was a pre-specified exclusion criterion. Also, the majority of patients were in NYHA class III and, therefore, the results may not be generally applicable to patients throughout the spectrum of heart failure. Additionally, Chaudhry et al did not assess any other clinical variables, such as shortness of breath or peripheral edema, which may also predict heart failure hospitalization. No conclusion can, therefore, be drawn about the relative contribution of weight gain over other clinically-reported symptoms in predicting heart failure hospitalization. However, the study is strengthened by how well the patients were matched with controls.
This study sets the stage for a new era in heart failure trials utilizing remote monitoring for prevention of hospitalization. Chaudhry et al conclude that increases in body weight in a heart failure population are associated with hospitalization for heart failure, and that these changes are seen at least a week before admission. Remote monitoring of weight may identify a high-risk period during which interventions to avert decompensated heart failure may be beneficial.