Abstract
Background
Red cell distribution width (RDW), an automated measure of variability in red blood cell size on full blood count (FBC), has recently emerged as a strong independent predictor of mortality in large population studies as well as several disease states. We wanted to determine the prognostic value of RDW in patients following a hip fracture - a condition associated with high mortality. This relationship has not been assessed to date.
Methods
We examined the relationship between admission RDW and all-cause mortality on 1-year follow-up, in consecutive hip fracture cases who presented between January 2007 and November 2009. We used Cox regression analysis to adjust for baseline Haemoglobin (Hb), Mean corpuscular Volume (MCV), creatinine, age, gender, ASA grade, Charlson index, pre-morbid independence level, Mental test score (MTS), delay to surgery and post-operative cardio-respiratory complication.
Results
Of 577 consecutive patients there were 377 females, 199 males; median age 81.4y. Seventeen (3%) were lost to follow-up at 1-year but were coded as survivor. One-year mortality was 23% overall. Unadjusted mortality was 12%, 15%, 29% and 35% in quartiles of increasing RDW. Along with age, gender, MTS, post-op cardiac or respiratory complication, Charlson index and ASA score, RDW remained a significant independent predictor of 120-day mortality (adjusted hazard ratio (HR): 1.211, 95% CI: 1.062–1.380, p=.004), as well as 1-year mortality (HR: 1.142, 95% CI: 1.032–1.263, p=.01). We repeated analysis excluding those lost to follow-up and this did not alter its predictive value. A third analysis in non-anaemic patients (n=464) showed that RDW remained an independent predictor of mortality on multivariate analysis (HR: 1.201, 95% CI: 1.039–1.389, p=.013).
Conclusion
RDW, a widely-available parameter on full blood count, is a significant independent predictor of short and long-term mortality following hip fracture, regardless of age, co-morbidity or anaemia status.
