JC Theis (Dunedin, New Zealand)
Data from the NZJR for all primary THAs performed between 1999 and 2013 was collected. This included THAs performed acutely and electively, in public and private institutions. THAs were divided into 3 groups (Cemented, hybrid and uncemented) and their 30-day mortality rate calculated. Patient factors (age, sex and ASA score) and institution (Public and private hospitals) were analysed. Using logistic regressions, odds ratios (OR) for each variable, their independent and combined effects on mortality were calculated.
Results : A total number of 90249 primary THAs were analysed of which 3374 were performed acutely. The cemented group (n=23082) had a mean 30-day mortality rate at 0.54%, the hybrid group (n=33773) was at 0.25% and the uncemented group (n=33394) was at 0.11%.
No gender difference was noted (0.3% 30-day mortality). Both the <55 year-old and the 55-65 year-old groups had a 0.1% 30-day mortality rate, which doubled for the 65-75 year-old group and was significantly increased to 0.7% (p<0.001) for the ≥ 75 year-olds.
An ASA 2 score carried a mortality rate of 0.1%, with a dramatic increase to 0.7% for ASA 3 and 2.8% for ASA 4. Compared to the ASA 1 group, 30-day mortality rate of the ASA 3 group was significantly raised (OR=31.9, p<0.0001). The risk of the ASA 4 group was highest (OR=140, p<0.0001). THAs performed acutely for fractures had a 5-fold increased 30-day mortality risk (OR= 5.34, p<0.005). The hybrid (OR=0.458) and uncemented groups (OR=0.198) achieved significantly better 30-day mortality rates compared to the cemented group (p<0.0001). When adjusted for all significant variables, the cemented group still carried a higher risk of 30-day mortality (p<0.003).
Conclusions : The 30-day mortality with any fixation method of THA shows that it is a very safe procedure, even though cementing resulted in a statistically higher mortality risk at 30 days when adjusted for all other risk variables.