Table 1.
Baseline characteristics of participants in treatment groups. Values are No/total No (%) unless stated otherwise
| Amoxicillin | Placebo | |
|---|---|---|
| Age (mean (SD)) | 44.7 (9.0), n=89 | 45.2 (9.0), n=91 |
| Women | 53/89 (60) | 52/91 (57) |
| Body mass index (mean (SD)) | 26.1 (4.1), n=89 | 25.9 (4.0), n=90 |
| Smoking, yes | 25/89 (28) | 21/89 (24) |
| Educational level: | ||
| Primary school (9 years) | 10/88 (11) | 9/89 (10) |
| High school (12 years) | 36/88 (41) | 42/89 (47) |
| College or university (<4 years) | 27/88 (31) | 18/89 (20) |
| University (≥4 years) | 15/88 (17) | 20/89 (22) |
| Comorbidity*: | ||
| Score 1 (back pain only) | 62/89 (70) | 60/91 (66) |
| Score 2 | 21/89 (24) | 27/91 (30) |
| Score >2 | 6/89 (7) | 4/91 (4) |
| Previous disc surgery | 18/89 (20) | 20/91 (22) |
| Emotional distress (HSCL-25≥1.75)† | 24/88 (27) | 23/91 (25) |
| FABQ physical activity (0-24)‡ (mean (SD)) | 11.2 (5.9), n=89 | 12.6 (5.8), n=90 |
| FABQ work (0-42)‡ (mean (SD)) | 17.0 (11.7), n=87 | 18.9 (12.0), n=89 |
| Duration of back pain (years) (median (IQR)) | 3.0 (1.5-5.6), n=89 | 3.4 (1.7-7), n=90 |
| Physical workload: | ||
| Mostly sitting | 37/77 (48) | 26/74 (35) |
| Job requires a lot of walking | 20/77 (26) | 20/74 (27) |
| Job requires a lot of walking and lifting | 17/77 (22) | 24/74 (32) |
| Job requires physically heavy work | 3/77 (4) | 4/74 (5) |
| Employment status: | ||
| Working full time | 46/89 (52) | 43/91 (47) |
| Partial sick leave | 14/89 (16) | 20/91 (22) |
| Complete sick leave | 22/89 (25) | 16/91 (18) |
| Disability pension | 3/89 (3) | 7/91 (8) |
| Unemployed | 2/89 (2) | 3/91 (3) |
| Student/other/unknown | 2/89 (2) | 2/91 (2) |
| Modic type 1 group | 58/89 (65) | 60/91 (66) |
| Level of Modic change and previous disc herniation: | ||
| L1/L2 | 0/89 | 0/91 |
| L2/L3 | 2/89 (2) | 2/91 (2) |
| L3/L4 | 7/89 (8) | 5/91 (5) |
| L4/L5 | 48/89 (54) | 29/91 (32) |
| L5/S1 | 58/89 (65) | 74/91 (81) |
SD=standard deviation; IQR=interquartile range.
*
Functional Comorbidity Index25; score increased by 1 for each of 18 diagnoses associated with decreased physical function.
†
Emotional distress (Hopkins Symptom Checklist 25); values ≥1.75 associated with psychiatric diagnosis.26
‡
Fear avoidance beliefs questionnaire27; higher values indicate more fear avoidance beliefs.