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Table 2 Overview of data collection

From: What factors explain the number of physical therapy treatment sessions in patients referred with low back pain; a multilevel analysis

Variables Measurement Used in analyses as
Gender Male; Female Categorical
Age Date of birth Continuous: years old at start treatment episode
Health insurance Public health insurance (Puhi), private health insurance (Prhi) Categorical: Puhi; Prhi; Unknown
Education Highest level of education: Primary school, secondary education, higher education, university Categorical: Low (primary); Middle (secondary, higher); High (university); Unknown
Urbanization rate 1 very high, 2 high, 3 moderate, 4 low, 5 very low Categorical: High (3+2+1); Low (5+4); Missing values (1.3%) recoded as high urbanization rate
Specialization of referring physician GP or Medical specialist Categorical: GP; Medical specialist
Reason for referral As given by letter by the referrer; coded with ICPC (26) by researchers Selection of patients with ICPC-code L03.00
Duration of complaint at start episode < 2 days; 2–7 days; 1 week – 1 month; 1–3 months; 3–6 months; 6 months – 1 year; 1–2 years; > 2 years; unknown Categorical: < 1 month; > 1 month; Missing values (1.0%) recoded as < 1 month
Recurrent complaint (appearing after a complaint-free episode of at least four weeks and at most two years) Yes; No; Unknown Categorical: Yes; No; Missing values (3.7%) recoded as no
Previous physical therapy for the same or other complaints in the last two years Yes; No; Unknown Categorical: Yes; No; Missing values (6.1%) recoded as no
Treatment goals Based on the International Classification of Functioning, Disability and Health (27); One main goal (out of 24) at the level of physical functions; One main goal at the level of activities (out of 11) 5 dichotomous variables; Missing values (0.6%) recoded as changing body position
Interventions Based on Dutch classification; three interventions at most (out of 25) applied in at least 50% of the sessions 5 dichotomous variables; Missing values (16.1%) integrated in reference category
Gender Male; Female Categorical: Male; Female; Missing values (2.1%) recoded as male
Age Date of birth Categorical: <45 years at January 1st, 2003; > 45 years at January 1st, 2003; Missing values (5.1%) recodes as > 45 years
Hours working per week Patient-related number of hours Categorical: <20 hours; 20–40 hours; >40 hours; Missing values (4.1%) recoded as 20–40 hours
Registration in quality register for manual therapy Yes; No Categorical: Yes; No
Additional training in LBP Yes; No Categorical: Yes; No; Missing values (4.1%) recoded as yes
Additional training in LBP guideline Yes; No Categorical: Yes; No; Missing values (4.1%) recoded as no
Feasibility of LBP guideline 1 item on questionnaire 10-point scale (1 = very bad; 10 = excellent; 7 = satisfactory) Categorical: <7 points; >7 points; Unknown
Time since graduation Date of graduation Categorical: < 20 years since graduation; > 20 years since graduation; Missing values (6.2% recodes as > 20 years.
Group size Number of therapists Categorical: Single handed; Group practice