An analysis of data from 4 decades offers insight into the impact of treatment advances and changes in risk factor management on incidence of hip fracture.
An analysis of 40 years of data from a cardiology study is offering clinicians insight into the factors that have led to a decrease in the incidence of hip fracture among patients since 1970.
Performed by investigators from the National Institutes of Health, results of the analysis further clarify the role lifestyle factors, such as smoking and heavy drinking, have in fracture risk but also detailed the effect of improved osteoporotic treatments in reducing fracture risk over time.
“The decrease in the hip fracture incidence that we observed over a long follow-up in large numbers of men and women may not be explained by better preventive treatment,” wrote study investigators. “Rather, it appears that birth cohort effects and improvement in lifestyle factors, particularly reduction in smoking, were prominent factors in the decrease in hip fracture rates over the 4 decades of our study.”
With the aim of clarifying how much therapeutic advances have contributed to the reduction in age-adjusted hip fracture incidence in the US, an NIH-led team designed their study as an analysis of the Framingham Heart Study. Conducted between 1970 and 2010, the Framingham Heart Study provided information related to more than 100,000 person-years of follow-up data from 10,552 individuals—4918 men and 5634 women.
Based on data from the study, investigators created 5-year calendar periods for examination beginning in 1971 for comparisons in the current analysis. Investigators noted age-period-cohort analysis tools were used to calculate net change in age-adjusted incidence over time. To limit confounding and impact of covariates, investigators ascertained presence or absence of risk factors through information collected in physical exams and questionnaires in the Framingham Heart Study.
Over the course of the 40-year study period, the age-adjusted incidence of hip fracture decreased significantly at a rate of 4.4% (95% CI, 6.8-1.9% per year. Results indicated this apparent decreased was significant for both men (5.2%; 95% CI, 9.1-1.1%) and women (4.5%; 95% CI, 7.0-2.0%). Investigators both period associations (P <.001) and birth cohort associations (P <.001) were statistically significant.
During the follow-up period, decreases in hip fracture incidence appeared to coincide with decreases in smoking and heavy drinking. In 1970, data from the Framingham Heart Study suggests the rate of smoking among participants was 38% while that figure decreased to 15% by the late 2000s. Similarly, 7% of the study cohort reported heavy drinking in the 1970s and that figure decreased to 4.5% in the late 2000s. Investigators also pointed out prevalence of other risk factors, including obesity, being underweight, and early menopause, were all stable during the study period.
When assessing incidence of hip fracture in analyses with patients who never smoked, investigators observed a difference of -3.2% per year. Investigators noted the difference between the decrease of the entire population and nonsmokers of 1.5% per year was similar to the hazard ratio conferred by smoking (HR, 1.5; 95% CI 1.14-1.96).
“Attributing the decrease in hip fracture incidence up to 2010 solely to better treatment is not supported by these data, emphasizing the need to treat patients with osteoporosis while continuing to encourage public health interventions for smoking cessation and heavy drinking,” wrote investigators.
Investigators noted multiple limitations within their study, the most significant being the lack of contemporaneous bone mineral density data across the study period. Other limitations noted by investigators include inability to determine if prevalence of osteoporosis decreased independently of other factors, study data on medications was limited to 1970-2000, and the exclusively white population of the Framingham Heart Study.
This study, “Incidence of Hip Fracture Over 4 Decades in the Framingham Heart Study,” was published in JAMA Internal Medicine.