2.5. Individual factors
Age, gender, BMI, smoking habits and LBPi were retrieved from
the questionnaire, interview and anthropometric measurements.
Smoking habits were obtained through the question ‘Do you
smoke?’ with response possibilities: daily smoking, occasionally
smoking, formerly smoked, never smoked. Smoking habits were
dichotomized into smokers (daily and occasionally smoking) and
non-smokers (formerly and never smoked). LBPi was self-rated and
defined as of the worst intensity of LBP during the last three
months on a numeric rating scale ranging from 0 (no pain) to 10
(worst imaginable pain) (Kuorinka et al., 1987). Subsequently, LBPi
was following dichotomized into low (5) and high (>5) categories
of LBPi (Andersen et al., 2012).