The Common Factor in Models Trying to Predict COPD: Smoking

With the growing worldwide burden of chronic obstructive pulmonary disease (COPD), researchers in Australia recently reviewed literature looking for the best models to predict this disease, in an effort to identify new preventive strategies. Out of thousands of articles, the common denominator boiled down to one thing: smoking.

COPD is projected to rank seventh in worldwide disease burden and as the third leading cause of death by 2030. Current guidelines in Australia, as well as the United States and the United Kingdom, do not recommend screening asymptomatic adults for COPD.

Of 4481 records identified, 30 articles were selected for full-text review, and only 4 were ultimately selected, the researchers wrote.

The only consistent predictor across all 4 models was a measure of smoking, although the researchers noted that overall, none of the models were particularly useful in accurately predicting future risk of COPD, and more studies are needed, particularly ones that include the effects of early life and childhood factors. For instance, there is increasing evidence that low birth weight affects the risk of asthma in middle age, they noted.

Besides smoking, other risk factors for COPD include occupational exposures to gases, dusts, and fumes, as well as genetic factors, such as alpha-1-antitrypsin deficiency.

The 4 models differed significantly in predictors used, outcome definitions, and populations from which they were developed, the researchers wrote, but few were validated in external populations. Just 1 included novel risk factors such as genetic markers.

Three models were developed in Western countries and the fourth in China, which now consumes over a third of the world’s tobacco; men there have a rapidly increasing death rate from tobacco-related causes.

All studies included sex in their final models; 2 studies derived separate models for females and males.

Interestingly, 1 model identified that smoking in women led to a greater increase in risk of COPD than it did for men.

In the US, more women are affected by COPD than men; evidence suggests that women are more susceptible to the risks of smoking and occupational exposures, as they are more affected by toxins due to their smaller airway size. Another possible explanation is the role of hormonal factors during perimenopause and postmenopause, which are associated with a more rapid decline in lung function and may increase the risk of COPD in older women.

Only 1 model included a socioeconomic status, defined by a regional measure of deprivation. Alternative options include measures of educational level, income level, or number of people living in the home.

The researchers were also surprised that only 1 model included lung function status.

More predictive models are needed, they said. None of the models were particularly accurate at predicting future risk of COPD, nor were they good at ruling out future COPD risk.

Reference

Matheson M, Bowatte G, Perret JL, et al. Prediction models for the development of COPD: a systematic review [published online June 14, 2018]. Int J Chron Obstruct Pulmon Dis. 2018;13:1927-1935. doi: 10.2147/COPD.S155675.