Relative contributions of modifiable risk factors to erectile dysfunction: results from the Boston Area Community Health (BACH) Survey

Abstract

Objectives: The objective of this study was to determine the relative contribution of modifiable risk factors (physical activity, smoking, and alcohol consumption) to inter-subject variation in erectile dysfunction (ED).

Methods: The Boston Area Community Health (BACH) Survey used a multistage stratified random sample to recruit 2301 men age 30-79 years from the city of Boston between 2002 and 2005. ED was assessed using the 5-item International Index of Erectile Function (IIEF-5). Multiple linear regression models and R(2) were used to determine the proportion of the variance explained by modifiable risk factors.

Results: In unadjusted analyses, lifestyle factors accounted for 12.2% of the inter-subject variability in IIEF-5 scores, comparable to the proportion explained by comorbid conditions (14.7%) and socioeconomic status (9%). Lifestyle factors were also significantly associated with age, comorbid conditions and socioeconomic status (SES). A multivariate model including all covariates associated with ED explained 29% of the variance, with lifestyle factors accounting for 0.9% over and above all other covariates in the model. Analyses repeated in a subgroup of 1215 men without comorbid conditions show lifestyle factors accounting for 2.5% of the variance after accounting for all other variables in the model.

Conclusions: Results of the present study demonstrate the contribution of modifiable lifestyle factors to the prevalence of ED. These results suggest a role for behavior modification in the prevention of ED.

Figure 1

IIEF-5 score explained variance. Explained variance from unadjusted models (R²_{Unadjusted model}) including only individual variable (e.g. age) or groups of variables (e.g. lifestyle) of interest. Explained variance due to each group over and above all other covariates determined as the difference between the R² from the full model including all covariates and a reduced model with the group or variable of interest removed: ΔR² = R²_{Full model} – R²_{Reduced model}. Boston Area Community Health (BACH) Survey 2002-2005.

Figure 2

Age, comorbidity, and socioeconomic status (SES) by lifestyle factors: physical activity, pack-years of smoking, alcohol consumption. Boston Area Community Health (BACH) Survey 2002-2005.