Preoperative red cell distribution width: Not a useful prognostic indicator for 30-day mortality in patients who undergo major- or ultra-major noncardiac surgery

Association of preoperative red blood cell width and postoperative 30-day mortality in patients undergoing non-cardiac surgery: a retrospective cohort study using propensity-score matching

BACKGROUND

In terms of predicting surgery mortality, it is controversial whether red blood cell width works independently. In non-cardiac surgery patients older than 18 years, we intend to examine the relationship between red blood cell width and postoperative 30-day mortality.

METHODS

In this retrospective cohort study, 90,785 Singapore General Hospital patients were matched by propensity score between January 1, 2012 and October 31, 2016. It was determined that red blood cell width at baseline and mortality within 30 days after surgery were the independent and dependent variables. We used a non-parametric multivariate logistic regression to balance the confounders among 7807 patients with high RDW and 7807 patients with non-high RDW in the propensity score matching. We investigated the association between RDW and 30-day mortality after surgery using the doubly robust estimation method.

RESULTS

Cohorts matched according to propensity score, the risk of 30-day mortality after surgery increased by 114.6.0% among the high RDW group (OR = 2.146, 95% CI 1.645-2.799, P < 0.00001). In the crude model, there was a significant association between RDW and 30-day mortality after surgery (OR = 1.877, 95% CI 1.476-2.388, P < 0.00001). In the propensity-score adjusted model, the risk of 30-day mortality after surgery in the high RDW group compared to the control group was not as high as in the non-adjusted model (OR = 1.867, 95% CI 1.467-2.376, P < 0.00001). Compared to non-high RDW group, the risk of 30-day mortality after surgery increased by 117.0% and 127.7% among high RDW group in the original cohort (OR 2.170, 95% CI 1.754-2.683, P < 0.00001) and the weighted cohort (OR 2.272, 95% CI 2.009-2.580, P < 0.00001), respectively.

CONCLUSIONS

According to the results of this observational, propensity score-matched cohort study, uncontrolled high RDW before surgery is associated with an increased risk of death within 30 days after surgery, that is to say, patients over the age of 18 with high preoperative RDW who undergo non-cardiac surgery have a worse postoperative prognosis than those with normal RDW.

Exploring red cell distribution width as a potential risk factor in emergency bowel surgery—A retrospective cohort study

Increased preoperative red cell distribution width (RDW) is associated with higher mortality following non-cardiac surgery in patients older than 65 years. Little is known if this association holds for all adult emergency laparotomy patients and whether it affects 30-day or long-term mortality. Thus, we examined the relationship between increased RDW and postoperative mortality. Furthermore, we investigated the prognostic worth of anisocytosis and explored a possible association between increased RDW and frailty in this cohort. We conducted a retrospective, single centre National Emergency Laparotomy Audit (NELA) database study at St Mary’s Hospital Imperial NHS Trust between January 2014 and April 2018. A total of 356 patients were included. Survival models were developed using Cox regression analysis, whereas RDW and frailty were analysed using multivariable logistic regression. Underlying model assumptions were checked, including discrimination and calibration. We internally validated our models using bootstrap resampling. There were 33 (9.3%) deaths within 30-days and 72 (20.2%) overall. Median RDW values for 30-day mortality were 13.8% (IQR 13.1%-15%) in survivors and 14.9% (IQR 13.7%-16.1%) in non-survivors, p = 0.007. Similarly, median RDW values were lower in overall survivors (13.7% (IQR 13%-14.7%) versus 14.9% (IQR 13.9%-15.9%) (p<0.001)). Mortality increased across quartiles of RDW, as did the proportion of frail patients. Anisocytosis was not associated with 30-day mortality but demonstrated a link with overall death rates. Increasing RDW was associated with a higher probability of frailty for 30-day (Odds ratio (OR) 4.3, 95% CI 1.22–14.43, (p = 0.01)) and overall mortality (OR 4.9, 95% CI 1.68–14.09, (p = 0.001)). We were able to show that preoperative anisocytosis is associated with greater long-term mortality after emergency laparotomy. Increasing RDW demonstrates a relationship with frailty. Given that RDW is readily available at no additional cost, future studies should prospectively validate the role of RDW in the NELA cohort nationally.

Red Cell Distribution Width as a Severity Marker on the Outcome of Patients with Acute Kidney Injury on Renal Replacement Therapy

Background

Acute kidney injury (AKI) requiring dialysis is associated with high mortality and morbidity. Red blood cell distribution width (RDW) has been shown as a predictor of mortality in different subsets of patients admitted to intensive care unit (ICU). This study compares the predictive ability of RDW and other severity illness prognostic models on 30 days mortality in adult patients admitted to ICUs with AKI necessitating dialysis.

Materials and methods

Thirty patients were evaluated using five different prognostic scoring models. Sequential organ failure assessment (SOFA) score, acute tubular necrosis-individual severity index (ATN-ISI), version II of acute physiology and chronic health evaluation (APACHE II), vasoactive-inotropic score (VIS), version II of simplified acute physiology score (SAPS II), and RDW as a marker were used to prognosticate the severity of illness. The scores were calculated using the values of clinical and laboratory parameters at the time of admission.

Results

The prognostic abilities of the scores were compared for their discriminatory power using receiver-operating characteristic (ROC) curves. The area under the ROC curve (AROC) of RDW was 0.904, SOFA score was 0.828, ATN-ISI was 0.743, SAPS was 0.857, and APACHE II score was 0.828. Vasoactive-inotropic score has the lowest discriminatory power with AROC of 0.487. Red blood cell distribution width has a strong and significant correlation with APACHE II and SOFA scores and a weak relation with ATN-ISI score and SAPS II.

Conclusion

Red blood cell distribution width has a better predictive ability than other disease severity scoring systems to predict mortality in an adult AKI patient admitted to ICU with need for renal replacement therapy (RRT).

How to cite this article

Nanjarapalle S, Samantaray A, Vishnubhotla S. Red Cell Distribution Width as a Severity Marker on the Outcome of Patients with Acute Kidney Injury on Renal Replacement Therapy. Indian J Crit Care Med 2020;24(2):95–98.