I came across two interesting papers in a recent issue of the BMJ, (5th July).
One dealt with regional vs. general anaesthesia for hip fracture surgery. In this retrospective review of electronic records of 73,284 patients, the primary outcome was in-patient mortality. I thought the results would favour surgery, but the mortality rate of about 2% did not differ significantly by type of anaesthesia, irrespective of whether or not the results were adjusted for patient and hospital variables. That said, the point estimate favoured the regional method (observed risk ratio was 10% lower). The confidence limits ‘excluded’ a difference of about 20%, meaning that an improvement in survival of about 0.4 percentage points was ‘compatible’ with the data. To put this in a more scientific way, a person who a priori thought that regional anaesthesia would improve mortality by somewhere between 0% and 20% should now be more confident in that view. In short, even with over 1,500 deaths, the study could be considered underpowered and a 10% (0.2 percentage point) improvement in mortality is quite likely. Mean survival after hip fracture is ~6 years, so life year gains might be over 1 per 100 patients. Regional anaesthesia would be cost-effective on these grounds alone if its incremental cost was less than £200 per patient. I would like to add more data by comparing death rates in other databases, including the English HES (hospital episode statistics) database.
The other paper compared the effect on mortality of eight different types of interventional procedure vs. medical treatment alone in patients with stable coronary artery disease. The point estimate favoured the interventional procedure in each case and, as might be expected, there was a highly significant class effect when the data were pooled. This treatment overview was based on direct and indirect comparisons in a network meta-analysis.
— Richard Lilford, CLAHRC WM Director
- Patorno E, Neuman MD, Schneeweis S, Mogun H, Bateman BT. Comparative safety of anesthetic type for hip fracture surgery in adults: retrospective cohort study. BMJ. 2014; 348: g4022.
- Trombetti A, Herrmann F, Hoffmeyer P, Schurch MA, Bonjour JP, Rizzoli R. Survival and potential years of life lost after hip fracture in men and age-matched women. Osteoporos Int. 2002; 13(9):731-7.
- The European Myocardial Revascularisation Collaboration. Revascularisation versus medical treatment in patients with stable coronary artery disease: network meta-analysis. BMJ. 2014; 348: g3859.