Time Series Analysis of Congestive Heart Failure Discharges in Florida Post Tropical Cyclones

Abstract

Purpose: Natural disasters can inflict devastating consequences on affected regions. The health systems role in disasters is often more reactionary than preventative. Literature in disaster medicine, particularly post hurricanes, typically focuses on the effects of natural disasters after a single event and on acute conditions rather than exacerbations of chronic conditions over time. This study analyzes congestive heart failure (CHF) discharges in Florida post tropical cyclones from 2007 to 2017 to understand the effects of these cyclones on health outcomes related to chronic cardiac disease. Methods: This is a retrospective longitudinal time series analysis of hospital CHF discharges across Florida using the publicly available Healthcare Cost and Utilization Project database. Patients with ICD9 and 10 codes for CHF were included. Due to the seasonality of the data and concerns for auto correlation, the auto regressive integrated moving average (ARIMA) model was used. Seasonal regressor variables and correlated variables such as cyclone frequency, maximum cyclone wind speed, average temperature and reports of influenza-like illness (ILI) were added to the model. Results: This study identified 3,372,993 patients discharged from hospitals in Florida with CHF from 2007 to 2017. Average age in each quarter ranged from 72.2 to 73.9 years, with overall mortality ranging from 4.3% to 6.4%. CHF discharges fluctuated every year with peak discharges from October to December and nadiring from April to June and an increasing overall time trend. Significant correlation with CHF discharge was found with the average temperature in the state (p=<0.01), approximately 208.7 less CHF discharges (SE=76.8) per degree of increase in temperature. However, no significant correlation was found between frequency of cyclones, the maximum wind speed and ILI reported with CHF discharges. Conclusions: This study suggests no significant increase in overall state burden of CHF discharge diagnosis as a result of recent previous cyclone occurrences. Further work is warranted to improve research methods for better management of the chronically ill during and after natural disasters.