Characteristics of the included trials
| First author | Intervention group at baseline | Control group at baseline | Intervention versus control programme | Outcome scales, week of reassessment |
| Al Rashoud 201431 | N: 26 Women: 62% Age: 52 years BMI: 38 VAS pain: 64 mm K/L: - | N: 23 Women: 65% Age: 56 years BMI: 37.1 VAS pain: 59 mm K/L: - | 3 weeks of exercise therapy, advice and LLLT versus 3 weeks of exercise therapy, advice and sham LLLT | Pain: VAS (movement) Disability: SKFS QoL: – Week of assessment: 2, 3, 9, 29 |
| Alfredo 2011/201829 52 | N: 24 Women: 75% Age: 61.15 years BMI: 30.16 VAS pain: 53.2 mm K/L: 3 | N: 22 Women: 80% Age: 62.25 years BMI: 29.21 VAS pain: 35.4 mm K/L: 2 | 3 weeks of LLLT followed by 8 weeks of exercise therapy versus 3 weeks of sham LLLT followed by 8 weeks of exercise therapy | Pain: WOMAC Disability: WOMAC QoL: – Week of assessment: 3, 11, 24, 37 |
| Alghadir 201432 | N: 20 Women: 50% Age: 55.2 years BMI: 32.34 VAS pain: 74.5 mm K/L: 2 | N: 20 Women: 40% Age: 57 years BMI: 33.09 VAS pain: 75.5 mm K/L: 2 | 4 weeks of exercise therapy, heat packs and LLLT versus 4 weeks of exercise therapy, heat packs and sham LLLT | Pain: WOMAC Disability: WOMAC QoL: – Week of assessment: 4 |
| Bagheri 201123 | N: 18 Women: 83.13% Age: 58.32 years BMI: 28.87 VAS pain: 67 mm K/L: – | N: 18 Women: 83.13% Age: 56.14 years BMI: 27.66 VAS pain: 59 mm K/L: – | 2 weeks of exercise therapy, therapeutic ultrasound, TENS and LLLT versus 2 weeks of exercise therapy, therapeutic ultrasound, TENS and sham LLLT | Pain: WOMAC (VAS) 0–100 Disability: WOMAC QoL: – Week of assessment: 2 |
| Bülow 199420 | N: 14 Women: – Age: – BMI: – VAS pain: 65.08 mm K/L: – | N: 15 Women: – Age: – BMI: – VAS pain: 56.35 mm K/L: – | 3 weeks of LLLT versus 3 weeks of sham LLLT | Pain: 0–121 Likert scale (movement/rest) Disability: – QoL: – Week of assessment: 3, 6 |
| Delkhosh 201839 | N: 15 Women: 100% Age: 55.9 years BMI: 26.5 VAS pain: 57 mm K/L: – | N: 15 Women: 100% Age: 58.3 years BMI: 27.8 VAS pain: 45 mm K/L: – | 2 weeks of exercise therapy, therapeutic ultrasound, TENS and LLLT versus 2 weeks of exercise therapy, therapeutic ultrasound, TENS and sham LLLT | Pain: VAS Disability: WOMAC QoL: – Week of assessment: 2, 8 |
| Fukuda 201130 | N: 25 Women: 80% Age: 63 years BMI: 30 VAS pain: 61 mm K/L: 2 | N: 22 Women: 64% Age: 63 years BMI: 30 VAS pain: 62 mm K/L: 2 | 3 weeks of LLLT versus 3 weeks of sham LLLT | Pain: VNSP (movement) Disability: Lequesne QoL: – Week of assessment: 3 |
| Gur 200333 (1.5 J) | N: 30 Women: 83.3% Age: 58.64 years BMI: 31.17 VAS pain: 73.2 mm K/L: 2 | N: 30 Women: 80% Age: 60.52 years BMI: 30.27 VAS pain: 67.4 mm K/L: 2 | 14 weeks of exercise therapy and 2 weeks of LLLT versus 14 weeks of exercise therapy and 2 weeks of sham LLLT | Pain: VAS (movement) Disability: – QoL: – Week of assessment: 6, 10, 14 |
| Gur 200333 (1 J) | N: 30 Women: 76.7% Age: 59.8 years BMI: 28.49 VAS pain: 74.4 mm K/L: 2 | N: 30 Women: 80% Age: 60.52 years BMI: 30.27 VAS pain: 67.4 mm K/L: 2 | 14 weeks of exercise therapy and 2 weeks of LLLT versus 14 weeks of exercise therapy and 2 weeks of sham LLLT | Pain: VAS (movement) Disability: – QoL: – Week of assessment: 6, 10, 14 |
| Gur and Oktayoglu | N: 40 Women: 75% Age: 58.2 years BMI: 29.11 VAS pain: 88 mm K/L: 3 | N: 40 Women: 72.5% Age: 58.26 years BMI: 30.11 VAS pain: 92 mm K/L: 3 | 14 weeks of exercise therapy and 2 weeks of LLLT versus 14 weeks of exercise therapy and 2 weeks of sham LLLT | Pain: VAS (movement) Disability: – QoL: – Week of assessment: 6, 10, 14 |
| Gworys 201218 | N: 34 Women: – Age: 57.6 BMI: – VAS pain: 54 mm K/L: – | N: 31 Women: – Age: 67.7 BMI: – VAS pain: – K/L: – | 2 weeks of LLLT versus 2 weeks of sham LLLT | Pain: VAS Disability: Lequesne QoL: – Week of assessment: 2 |
| Hegedűs 200953 | N: 18 Women: – Age: – BMI: – VAS pain: 57.5 mm K/L: 2 | N: 17 Women: – Age: – BMI: – VAS pain: 56.2 mm K/L: 2 | 4 weeks of LLLT versus 4 weeks of sham LLLT | Pain: VAS Disability: – QoL: – Week of assessment: 4, 6, 12 |
| Helianthi 201654 | N: 30 Women: 60% Age: 69 years BMI: 25.8 VAS pain: 60.2 mm K/L: 3 | N: 29 Women: 82.8% Age: 68 years BMI: 26.3 VAS pain: 54.1 mm K/L: 3 | 5 weeks of LLLT versus 5 weeks of sham LLLT | Pain: VAS (movement) Disability: Lequesne QoL: – Week of assessment: 2, 5, 7 |
| Hinman 201441 | N: 71 Women: 39% Age: 63.4 years BMI: 30.7 VAS pain: 41.5 mm K/L: – | N: 70 Women: 56% Age: 63.8 years BMI: 28.8 VAS pain: 43 mm K/L: – | 12 weeks of LLLT versus 12 weeks of sham LLLT | Pain: WOMAC Disability: WOMAC QoL: AQoL-6D Week of assessment: 12, 52 |
| Jensen 198721 | N: 13 Women: – Age: – BMI: – VAS pain: 67 mm K/L: – | N: 16 Women: – Age: – BMI: – VAS pain: 72.6 mm K/L: – | 1 week of LLLT versus 1 week of sham LLLT | Pain: 0–21 (movement) Disability: – QoL: – Week of assessment: 1 |
| Kheshie 201447 | N: 18 Women: 0% Age: 56.56 years BMI: 28.62 VAS pain: 76.8 mm K/L: 2.5 | N: 15 Women: 0% Age: 55.6 years BMI: 28.51 VAS pain: 78.7 mm K/L: 2.5 | 6 weeks of exercise therapy and LLLT versus 6 weeks of exercise therapy and sham LLLT | Pain: WOMAC Disability: WOMAC QoL: – Week of assessment: 6 |
| Koutenaei 201755 | N: 20 Women: 85% Age: 52.3 years BMI: 28.4 VAS pain: 74 mm K/L: 3 | N: 20 Women: 80% Age: 53 years BMI: 28.6 VAS pain: 65.5 mm K/L: 3 | 2 weeks of exercise therapy and LLLT versus 2 weeks of exercise therapy and sham LLLT | Pain: VAS (movement) Disability: – QoL: – Week of assessment: 2, 4 |
| Mohammed 201856 | N: 20 Women: 85% Age: 55.25 years BMI:≥25 VAS pain: 70 mm K/L: 2 | N: 20 Women: 85% Age: 50.11 years BMI:≥25 VAS pain: 80 mm K/L: 2 | 4 weeks of LLLT versus 4 weeks of sham LLLT | Pain: VAS Disability: – QoL: – Week of assessment: 4 |
| Nambi 201648 | N: 17 Women: – Age: 58 BMI: 26.9 VAS pain: 78 mm K/L: 3.1 | N: 17 Women: – Age: 60 BMI: 28.3 VAS pain: 76 mm K/L: 3.2 | 4 weeks of exercise therapy, kinesio tape and LLLT versus 4 weeks of exercise therapy, kinesio tape and sham LLLT | Pain: VAS Disability: – QoL: – Week of assessment: 4, 8 |
| Nivbrant 199219 | N: 15 Women: 69.2% Age: 69 years BMI: – VAS pain: 67 mm K/L: – | N: 15 Women: 84.6% Age: 66 years BMI: – VAS pain: 58 mm K/L: – | 2 weeks of LLLT versus 2 weeks of sham LLLT | Pain: VAS (movement) Disability: Walking disability QoL: – Week of assessment: 2, 3, 6 |
| Rayegani 201243 | N: 12 Women: 83.3% Age: 61.7 years BMI: – VAS pain: 63 mm K/L:<4 | N: 13 Women: 92.3% Age: 61.2 years BMI: – VAS pain: 52 mm K/L:<4 | 2 weeks of LLLT versus 2 weeks of sham LLLT | Pain: WOMAC Disability: WOMAC QoL: – Week of assessment: 6, 14 |
| Tascioglu 200440 (3 J) | N: 20 Women: 70% Age: 62.86 years BMI: 27.56 VAS pain: 68 mm K/L: 2 | N: 20 Women: 65% Age: 64.27 years BMI: 29.56 VAS pain: 63.88 mm K/L: 2 | 2 weeks of LLLT versus 2 weeks of sham LLLT | Pain: WOMAC Disability: WOMAC QoL: – Week of assessment: 3, 26 |
| Tascioglu 200440 (1.5 J) | N: 20 Women: 75% Age: 59.92 years BMI: 28.63 VAS pain: 65.72 mm K/L: 2.5 | N: 20 Women: 65% Age: 64.27 years BMI: 29.56 VAS pain: 63.88 mm K/L: 2 | 2 weeks of LLLT versus 2 weeks of sham LLLT | Pain: WOMAC Disability: WOMAC QoL: – Week of assessment: 3, 26 |
| Youssef 201642 (904 nm) | N: 18 Women: 66.7% Age: 67.5 BMI:<40 VAS pain: 51.67 mm K/L: 2 | N: 15 Women: 66.7% Age: 66.3 years BMI:<40 VAS pain: 50 mm K/L: 2 | 8 weeks of exercise therapy and LLLT versus 8 weeks of exercise therapy and sham LLLT | Pain: WOMAC Disability: WOMAC QoL: – Week of assessment: 8 |
| Youssef 201642 (880 nm) | N: 18 Women: 61.1% Age: 67.3 BMI: <40 VAS pain: 52.50 mm K/L: 2 | N: 15 Women: 66.7% Age: 66.3 years BMI: <40 VAS pain: 50 mm K/L: 2 | 8 weeks of exercise therapy and LLLT versus 8 weeks of exercise therapy and sham LLLT | Pain: WOMAC Disability: WOMAC QoL: – Week of assessment: 8 |
The values for age and body mass index (BMI) are means and the values for K/L grade are medians. Baseline Visual Analogue Scale (VAS) scores have been extracted or estimated as described in the Method section. Week of assessment in bold denotes time point used for the main meta-analyses.
AQoL-6D, Assessment of Quality of Life 6 Dimensions; DIQ, Disability Index Questionnaire; K/L, Kellgren/Lawrence; LLLT, low-level laser therapy; NRS, Numeric Rating Scale; QoL, quality of life; SKFS, Saudi Knee Function Scale; TENS, Transcutaneous Electrical Nerve Stimulation; VNPS, Visual Numerical Pain Scale; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index.