Baseline Characteristics: The patients were randomly divided into three groups, red light group, 15 patients (10 women, 5 men); infrared light group, 18 patients (13 women, 5 men); and placebo group, 17 patients (11 women, 6 men). There was no significant age difference between groups (P = 0.88).
Pain elevation before treatment, using SF-MPQ sensory, affective, and total components, did not show statistically significant between group differences (P = 0.46, P = 0.89, P = 0.69, respectively). No differences in pain evaluation between the groups before treatment were found using the PPI and VAS methods (P = 0.13, and P = 0.49, respectively). The degree of disability before treatment, evaluated by the DIQ method, was not statistically different between the three groups (p = 0.68).
Pain Evaluation after Treatment: Significant pain reduction (Table 2) was found in the red and infrared light groups, but not in the placebo treated group, in all three pain evaluation methods applied in this study (P < 0.05). No significant difference in pain relief was shown between the group treated with red light and the one treated with infrared light.
| TABLE 2. MEAN PAIN RATING VALUES OBTAINED WITH SHORT-FORM McGILL PAIN QUESTIONNAIRE (SF-MPQ), PRESENT PAIN INTENSITY (PPI) AND VISUAL ANALOGUE SCALE ADMINISTERED BEFORE AND AFTER TREATMENT WITH RED, INFRARED OR PLACEBO LIGHT EMITTERS. |
| Pain Test |
Red
(n=15) |
Infrared
(n=18) |
Placebo
(n=17) |
| SF-MPQ/Sensory |
| Before (SD) |
10.40 (8.98) |
10.78 (6.28) |
8.11(4.75) |
| After (SD) |
4.53 (6.98) |
5.27 (5.06) |
8.94 (4.84) |
| P value |
0.0001 |
0.00001 |
0.1635 |
| SF-MPQ/Affective |
| Before (SD) |
3.93 (3.69) |
4.27 (2.94) |
4.47 (3.31) |
| After (SD) |
1.60 (2.72) |
1.88 (2.32) |
4.00 (3.20) |
| P value |
0.001 |
0.0002 |
0.1635 |
| SF-MPQ/Total |
| Before (SD) |
14.27 (11.81) |
15.06(7.71) |
12.47(7.62) |
| After (SD) |
6.13 (9.63) |
7.33 (6.65) |
13.06(7.42) |
| P value |
0.00001 |
0.00001 |
0.3220 |
| PPI |
| Before (SD) |
3.13 (0.99) |
3.66 (0.68) |
2.88 (1.11) |
| After (SD) |
1.40 (0.98) |
1.16 (0.92) |
2.82 (0.88) |
| P value |
0.00001 |
0.00001 |
0.7175 |
| VAS |
| Before (SD) |
6.53 (2.47) |
7.16 (2.22) |
6.23 (2.41) |
| After (SD) |
3.33 (2.38) |
3.22 (2.62) |
6.29 (2.22) |
| P value |
0.00001 |
0.00001 |
0.8484 |
Disability Evaluation after Treatment: We observed significant functional improvement in both the red and infrared light groups as assessed by the DIQ method (Table 3, P < 0.05). No such improvement was observed in the placebo group. Disability indexes showed no difference between the red and infrared groups after the treatment.
| TABLE 3. MEANS DISABILITY INDEX VALUES OBTAINED WITH DISABILITY INDEX QUESTIONNAIRE (DIQ) ADMINISTERED BEFORE AND AFTER TREATMENT WITH RED, INFRARED, AND PLACEBO LIGHT EMITTERS. |
| DIQ |
Red
(n = 15) |
Infrared
(n -= 18) |
Placebo
(n = 17) |
| Before(SD) |
0.663(0.854) |
0.617(0.56) |
0.817(0.68) |
| After (SD) |
0.395(0.571) |
0.314(0.35) |
0.758(0.62) |
| P value |
0.0070 |
0.0001 |
0.2440 |
Follow up: After the end of the study, patients treated with red and infrared light emitters requested retreatment because of pain within 1 to 12 months (4.2 3.0 and 6.1 3.2 months for red and infrared, respectively). The pain relief period was significantly longer for these two groups in comparison to the placebo group (0.53 0.62 months, P < 0.05). The difference in the period of pain relief in the red and infrared groups was not significantly different (P = 0.41).
All patients treated with the placebo emitters required analgesic treatment within 2 months from the end of the study (9 immediately, 7 within 1 month and 1 within 2 months). Only seven patients in the other two groups required analgesic treatment within 2 months after the end of treatment. The remainder required treatment only after long periods: 15 within 6 months, 10 within 10 months, and one was free of pain 12 months after treatment. |
