THE EFFECT OF SMOKING ON THE OUTCOME AFTER TOTAL HIP REPLACEMENT

Abstract

Aim: To study the effect of smoking on the rate of complications and functional outcome after Total Hip Replacement (THR).

Methods: Data was prospectively collected for all patients undergoing a unilateral, primary THR in one hospital during the period 1998 to 2006 Data was collected at pre-operative assessment, in the peri-operative period and at 6 months, 18 months, 3 years and 5 years. Patients were placed in one of three groups; smokers, ex-smokers and those who had never smoked.

Outcome measures included rate of complications: infection, DVT, PE, length of hospital stay and Harris Hip Score (HHS).

Statistical analysis was undertaken to determine any correlation between smoking and these outcome measures using chi-squared tests, t-tests and multiple regression adjusting for confounding factors.

Results: 1765 patients underwent THR during the study period, of whom 635 were males and 1130 females, with a mean age at operation of 69.

268 patients (15%) were smokers, 582 patients (33%) were ex-smokers and 917 patients (52%) had never smoked. As there was little data available on when the ex-smokers had stopped smoking we studied current smokers compared to patients that had never smoked

There were no significant differences in complications such as DVT, PE, Deep infection and Superficial infection, these were all rare events. Neither was there any significant difference in hospital stay times. After adjusting for pre-operative HHS, age, sex and ASA status current smokers had significantly lower HHS at 6 months (p< 0.001, 95% confidence interval for effect size 1.6 to 5.3), and also showed a lower HHS at 18 months, 3 years and 5 years although not significantly so.

Conclusion: Current smokers have a significantly lower HHS post-operatively in comparison to non-smokers. In a health system where more and more patients wish to know the risk associated with potential operative interventions, we can now say that patients who smoke will have a poorer outcome post Total Hip Replacement. This may also allow us to discourage some patients wishing to have THR whom are poor operative candidates.

We plan to further analysis the data to try and ascertain why this is the case.