Geographic distribution of the incidence of osteonecrosis of the femoral head in Japan and its relation to smoking prevalence.

OBJECTIVES

Alcohol intake and smoking are modifiable lifestyle-related risk factors for osteonecrosis of the femoral head (ONFH). We investigated geographic differences in ONFH incidence in Japan and the correlation with alcohol intake and smoking to develop prevention strategies for ONFH in Japan.

METHODS

This ecological study was conducted in Japan primarily using the following data sources: nationwide epidemiological survey and national survey. We estimated the annual ONFH incidence and the prevalence of alcohol drinking and smoking in each prefecture. Prefectural incidence and prevalence were calculated by sex and age-standardization.

RESULTS

The mean annual ONFH incidence per 100,000 population was 3.08 in men and 1.63 in women, respectively. There was no significant correlation between ONFH incidence and the prevalence of any levels of alcohol intake, while smoking ≥20 cigarettes/day showed a significant and moderate correlation in men (r = 0.47, p = .01). This correlation remained significant after adjustment for the prevalence of any levels of alcohol intake (standardized partial regression coefficient = 0.47-0.49, p = .009-.01).

CONCLUSION

ONFH incidence is geographically variable in Japan, and this may be partly explained by the distribution of smoking prevalence. Smoking cessation may contribute to an effective decline in the overall ONFH incidence in Japan.