Effect of acute kidney injury on hospital-based outcomes in patients with multiple myeloma.
Authors: Zafar Muhammad Usman , Tarar Zahid , Ghous Ghulam , Farooq Umer , Lash Bradley Walter 
Published: June 2021

e20006

Background: Multiple Myeloma, a cancer of plasma cells, is treatable, but incurable. 5-year survival rate is about 54% depending upon the stage. Studies have suggested that up to 50% of the patients experience acute kidney injury or chronic kidney disease at some point in their disease course. Approximately 3% of the patients will end up on hemodialysis. In this study we utilize the National Inpatient Sample (NIS) to understand the effect of acute kidney injury (AKI) on inpatient mortality in multiple myeloma patients. Methods: This is a retrospective study utilizing the data obtained from the NIS for the year 2018. We queried this NIS database for ICD-10 codes for multiple myeloma or plasmacytoma that had not achieved remission or was in relapse. We also looked at codes for acute kidney injury as secondary diagnosis. Primary outcome was inpatient mortality. Secondary outcomes were hospital length of stay and cost utilization. We then ran multivariate logistic regression analysis in STATA MP 16.1. Various comorbidities were accounted for by adding them into the analysis. These included previous history of coronary artery disease, congestive heart failure, stroke, smoking, hyperlipidemia, stem cell transplant, neutropenia and chemotherapy. Results: The population of multiple myeloma patients under investigation were all adults more than 18 years of age and numbered in 3944 patients. The mean age was 65.71 years. Among these 45% were females. While examining inpatient mortality we see that for patients that had AKI the odds of inpatient mortality are higher (Odds Ratio (OR) 1.75, p = 0.003, 95% Confidence Interval (CI) 1.21 – 2.56). History of Heart Failure (OR 2.28, 95% CI 1.59 – 3.28), and increasing age (OR 1.02, 95% CI 1.01 – 1.04) also appear to contribute towards higher odds of mortality. The effect of other comorbidities was not statistically significant. Among demographical characteristics being of Native American heritage or not belonging to any descriptive race predicted higher odds of mortality. Mean LOS was 11 days. Patients with AKI stayed in the hospital longer by ̃1.4 days (Coef. 1.39, 95% CI 0.41 – 2.37). LOS was higher in patients with a history of heart failure (2.61, 95% CI 0.89 – 4.34 and in those with a history of neutropenia (5.52, 95% CI 4.42 – 6.62). LOS was lower in patients with a history of smoking by 1 day. Age lowered the LOS by a clinically insignificant amount. Teaching hospitals had higher LOS by ̃4 days. The total charge for hospitalizations from AKI is higher by $31019 (95% CI 14444.23 – 47594.37). Other factors incurring higher cost include history of neutropenia, and teaching hospitals. Hospitals in the Midwest had lower cost compared to hospitals in the Northeast. Conclusions: Among patients that present with a principal diagnosis of multiple myeloma, having acute kidney injury, adversely affects inpatient outcomes that include, mortality, hospital length of stay and total hospitalization cost.