Clustering of community-acquired pneumonia in hospitalised adults in the Christchurch Region: association with socio-economic deprivation.

Aim: Community-acquired pneumonia (CAP) is inequitably experienced in populations globally, with multiple social and environmental factors contributing to the risk of CAP; thus, predicting communities at increased risk is difficult. The aims of this study were to determine the geographical distribution of adults with CAP requiring hospitalisation in Christchurch, and to examine the associations between CAP and socio-economic and area deprivation.

Methods: A retrospective clinical records review was conducted of all adult patients hospitalised with CAP at Christchurch Hospital over a 12-month period. Geocoding residential addresses allowed for geospatial hotspot analysis using the Getis-Ord Gi* method. Comparison of the relative rates of CAP in different socio-economic deprivation deciles was assessed using New Zealand census data and the Index of Multiple Deprivation (IMD).

Results: The dataset comprised 924 hospitalisations. CAP hotspots were located in the northeast and southwest of the city. CAP was not equally distributed across the deprivation quantiles (p <0.001); compared with the least deprived quintile, quintiles four and five had rate ratios (95% confidence interval [CI]) of 1.5 (1.3 to 1.8) and 1.6 (1.3 to 2.0), respectively. Patients with CAP who identified as Māori or Pacific peoples were significantly younger, and a higher proportion were resident in areas of highest socio-economic deprivation relative to patients who identified as NZ European.

Conclusion: This study identified hotspots within Christchurch with higher rates of CAP requiring hospitalisation and has contributed further New Zealand-based evidence on the influence of socio-economic disparities on health inequity.