Table 1.
Quality assessment of interventional studies following GRADE and PICO criteria.
| Reference | Outcome of interest | Number of participants | Quality of evidence (GRADE) | Relative effect | Comparative risk (PICO) |
|
|---|---|---|---|---|---|---|
| Placebo group | Intervention group | |||||
| 25 | To determine the benefit of a tetrahydrocannabinol (THC)-rich cannabis oil on symptoms and quality of life of fibromyalgia patients | 17 (8 in the treatment group and 9 in the placebo group) | Moderate to low (a) | Fibromyalgia Impact Questionnaire (FIQ) mean scores: 75.5 to 30.5 points (p < 0.001) | Moderate to high-risk patients | Moderate to high-risk patients |
| 26 | Analgesic effects of inhaled pharmaceutical grade cannabis | 20 allocated to intervention, without placebo group | Moderate (b) | N/A | N/A | Moderate risk |
| 29 | Nabilone vs Amitriptyline. The primary outcome was sleeping quality, measured by the Insomnia Severity Index and the Leeds Sleep Evaluation Questionnaire. Secondary outcomes included pain, mood, quality of life, and adverse events | 32 (29 completed the study) | High (c) | Insomnia Severity Index difference = 3.2 (IC 95% = 1.2–5.3) Leeds Sleep Evaluation Questionnaire difference = 0.5 (0.0–1.0) (wakefulness) difference = 0.3 (−0.2–0.8) |
Moderate risk |
N/A |
| 47 | Nabilone in Fibromyalgia. Determine the benefit of nabilone in pain management and quality of life improvement | 40 and finished 33. (15 in the treatment group and 18 in the control group) | High | Visual Analog Scale (VAS) = −2.04, p < 0.02. Fibromyalgia Impact Questionnaire (FIQ) = −12.07, p < 0.02. Anxiety = −1.67, p < 0.02 |
Moderate risk | Moderate risk |
GRADE: Grading of Recommendations, Assessment, Development and Evaluation; PICO: patient, intervention, comparison, outcome; N/A (No applicable).
(a) It is a study with a small number of patients, all with high risk of FM and/or comorbidities, which makes it prone to selection and execution or information biases.
(b) There is randomization of patients for each visit and use of each treatment, but there is no clear masking and although they describe the use of placebo there is no clarity about the randomization in this group.
(c) It is a study with good randomization, blinded, crossover. 2 patients did not complete the study due to adverse effects and there was a large refusal of patients to enter the study, which possibly allowed the outcomes to be determined in a better way with clear inclusion and exclusion criteria. Although a CI contains 1, the study design and expected outcomes allow it to be of high quality.