Table 2 Demographic and clinical characteristics of participants according to pain group (no LBP and CLBP) and according to participation in the secondary study (responder and non-responder)

N (% within pain groups)

Age (years), mean (SD)

Female, N (%)

Highest level of education, N (%)

   Never attended school

   Some primary school

   Completed primary school

   Some secondary school

   Completed secondary school

   Trade certificate or diploma

   University degree

Age of onset of LBP (years), mean (SD)

Intensity of pain in last week, median (IQR) for NRS 0-10)

Episodes of LBP in the last year, N (%)

   1-3 episodes

   4-10 episodes

   > 10 episodes

Number of work days missed due to LBP, N (%)

   0 days

   1-2 days

   3-7 days

   15-30 days

   181-365 days

   no response

Impact of LBP, N (%) responding 'yes'

   Seeking health professional advice

   Using medication for pain

   LBP interfering with normal activities

   LBP interfering with recreational activities

ODI score (%), mean (SD)

FABQ-physical activity score [0-24], mean (SD)

FABQ-work score [0-42], mean (SD)

BBQ score [9-45], mean (SD)

CSQ catastrophizing score [0-24], mean (SD)

S-TOFHLA numeracy score [0-28], mean (SD)^{^}

S-TOFHLA reading comprehension score [0-72], mean (SD)^{^}

S-TOFHLA total score [0-72], mean (SD)^{^}