Estimated plasma volume and mortality: analysis from NHANES 1999-2014

While estimated plasma volume (ePV) has been studied in some diseases, such as heart failure, the relationship between ePV and all-cause or cause-specific mortality remains unexplored. Therefore, we investigated the association between ePV and all-cause, cardiovascular (CV), and cancer-related mortality among adults in the US.

We used the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2014 and included participants older than 18 years. Mortality data were obtained from the National Death Index and matched to the NHANES participants. ePV was derived using Strauss formula. Cox proportional hazard models were fit to estimate hazard ratios for all-cause and cause-specific mortality without and with adjustment for potential confounders.

Of the 42,705 participants, 5194 died (1121 CV deaths) during mean follow-up of 8.0 (range 0-16.7) years. Mean ± SD age and ePV of the participants were 47.2 ± 19.4 years and 4.2 ± 0.84, respectively. In unadjusted models, 1 unit increase in ePV was associated with 29%, 32%, and 16% increased risk in all-cause (HR 1.29; 95% CI 1.24, 1.35), CV (HR 1.32; 95% CI 1.22, 1.43), and cancer-related (HR 1.16; 95% CI 1.05, 1.27) mortality. Risk remained high in adjusted models (all-cause HR 1.24; 95% CI 1.18, 1.30; CV HR 1.22; 95% CI 1.11, 1.34; cancer-specific HR 1.24; 95% CI 1.10, 1.39). When comparing the highest and lowest ePV quartiles, similar results were noted (adjusted all-cause HR 1.64; 95% CI 1.45, 1.86; CV HR 1.52; 95% CI 1.19, 1.93; cancer HR 1.85; 95% CI 1.38, 2.49).

An increase in ePV was associated with increased all-cause and cause-specific mortality. Further studies are needed to explore the mechanism of this relationship and translation into a better outcome.