SF-6D utility scores of smokers and ex-smokers with or without respiratory symptoms attending primary care clinics

The aim of this paper is to find out generic preference-based Short-Form 6 Dimensions (SF-6D) utility scores of smokers and ex-smokers with varying cigarette exposure, with and without respiratory symptoms.

Seven hundred thirty one people aged ≥30 with a history of smoking who attended 5 public primary care clinics completed a cross-sectional survey using SF-6D utility score, Breathlessness, Cough, and Sputum Scale (BCSS©) and office spirometry.

Most of the subjects were men (92.5%) in an older age group (mean age 62.2 ± 11.7 years). About half of them (48.3%) were current smokers while the other half (51.7%) were ex-smokers. More than half of them (54.2%) reported mild respiratory symptoms (mean BCSS score 0.95 ± 1.12). The most common symptoms were sputum (45.1%), followed by cough (34.2%) and breathlessness (6.0%). The SF-6D overall utility score was 0.850 ± 0.106. The subjects reported significantly lower SF-6D scores when they had breathlessness (0.752 ± 0.138; p = < 0.001), cough (0.836 ± 0.107; p = 0.007), sputum (0.838 ± 0.115; p = 0.004) or any of the above symptom (0.837 ± 0.113; p < 0.001). In both groups of current smokers and ex-smokers, there was no statistically significant difference in the scores among light, moderate or heavy smokers. In the Tobit regression model of factors affecting SF-6D utility score, subjects who reported more respiratory symptoms (i.e. higher BCSS©) had lower SF-6D scores (B = − 0.018 ± 0.007, p < 0.001), while men had higher SF-6D scores than women (B = 0.037 ± 0.031, p = 0.019). Subjects who attended middle or high school had higher SF-6D score than those attended the University or above. The presence of airflow obstruction was not associated with the score.

The study yielded SF-6D utility scores of smokers and ex-smokers with different reported cigarette exposure, which could be useful in future clinical studies and cost-effectiveness analysis.