Carbon emissions and hospital pathology stewardship: a retrospective cohort analysis

As healthcare is responsible for 7% of Australia's carbon emissions, it was recognised that a policy implemented at St George Hospital, Sydney, to reduce non-urgent pathology testing to 2 days per week and, on other days only if essential, would also result in a reduction in carbon emissions. The aim of the study was to measure the impact of this intervention on pathology collections and associated carbon emissions and pathology costs.

To measure the impact of an intervention to reduce unnecessary testing on pathology collections and associated carbon emissions and pathology costs.

The difference in the number of pathology collections, carbon dioxide equivalents (CO₂ e) for five common blood tests and pathology cost per admission were compared between a 6-month reference period and 6-month intervention period. CO₂ e were estimated from published pathology CO₂ e impacts. Cost was derived from pathology billing records. Outcomes were modelled using multivariable negative binomial, generalised linear and logistic regression.

In total, 24 585 pathology collections in 5695 patients were identified. In adjusted analysis, the rate of collections was lower during the intervention period (rate ratio 0.90; 95% confidence interval (CI), 0.86-0.95; P < 0.001). This resulted in a reduction of 53 g CO₂ e (95% CI, 24-83 g; P < 0.001) and $22 (95% CI, $9-$34; P = 0.001) in pathology fees per admission. The intervention was estimated to have saved 132 kg CO₂ e (95% CI, 59-205 kg) and $53 573 (95% CI, 22 076-85 096).

Reduction in unnecessary hospital pathology collections was associated with both carbon emission and cost savings. Pathology stewardship warrants further study as a potentially scalable, cost-effective and incentivising pathway to lowering healthcare associated greenhouse gas emissions.