The possible effects of iron loss from bloodletting on mortality from pneumonia in the nineteenth century

Objective

To estimate iron losses and disease severity following 19th century bloodletting in patients with pneumonia.

Study design and setting

Benefits of bloodletting in pneumonia patients were contested during the 19th century. Although large blood volumes during infection were removed there was no systematic data collection assessing efficacy and knowledge of iron composition of blood was rudimentary. This observational analysis of historical data quantifies iron losses in pneumonia cases in relation to disease severity.

Results

Based on one detailed case series average blood volume removed for survivors was 830 ml (range 114 - 2272 ml), and mean recovery times were shorter in patients bled within 2 days of illness (p<0.001). Average iron removed was 446 mg with phlebotomy done ≤ 2 days of illness presentation and 347 mg after >2 days of illness (p=0.012). Across several European hospitals average case fatality in pneumonia patients receiving phlebotomy was higher than in those treated without phlebotomy (19.9% vs 12.8%, OR 1.55, 95% CI 1.38-1.74, P<0.001).

Conclusion

Variable efficacy for bloodletting could at least in part be explained by altered iron status.