Trends in Smoking Rates by Level of Psychological Distress-Time Series Analysis of US National Health Interview Survey Data 1997-2014

Introduction: People with mental health problems have high rates of smoking, and represent a large proportion of adult smokers in the United States. However, few public health programs in tobacco control address mental health. This study sought to determine if smoking is declining at comparable rates in people with different levels of psychological distress. Methods: Time series analysis of smoking prevalence between 1997 and 2014 was undertaken, by level of psychological distress, age group, and sex using data from the US National Health Interview Survey, a series of cross-sectional surveys. Exponential smoothing and auto-regressive integrated moving average (ARIMA) modeling were used to estimate trends over time. Results: Smoking prevalence has declined steadily in adults with no psychological distress. In males the smoking rate has dropped from 24.4% in 1997 to 16.6% in 2014 in the underlying trend series, a decline of 0.46 percentage points per year (95% confidence interval [CI]: 0.43-0.48), and in females from 18.4% to 11.3%, a decline of 0.42 percentage points per year (95% CI: 0.39-0.45). In males with high psychological distress there was a much smaller and statistically nonsignificant reduction of 0.08 percentage points per year (95% CI: -0.26-0.42) from 45.6% in 1997 to 44.9% in 2014, while in females the annual rate of decline was 0.29 percentage points (95% CI: -0.11-0.47) representing a smaller decline from 42.0% in 1997 to 37.7% in 2014. Conclusions: People with high levels of psychological distress continue to smoke at particularly high rates, and may benefit less from existing tobacco control measures. Implications: Rates of smoking have declined substantially over time in people with no or low levels of psychological distress and much smaller reductions have occurred in people with high levels of psychological distress. If this trend continues the disparity in smoking rates by levels of psychological distress will continue to rise. These results suggest people with high levels of psychological distress do not benefit to the same extent as others from existing tobacco control measures. Psychological distress and mental illness may be important considerations for future tobacco control efforts.