Nasiri M, Torkaman M, Feizi S, Shamloo MBB. Effect of aromatherapy with damask rose on alleviating adults' acute pain severity: A systematic review and meta-analysis of randomized controlled trials. Complement Ther Med. January 2021;56:102596. doi: 10.1016/j.ctim.2020.102596.
Damask rose (DR; Rosa damascena, Rosaceae), used medicinally since antiquity, was cited by the Persian physician Avicenna (980 – 1037 CE) for pain relief. Grown in Iran, Europe, Bulgaria, Turkey, and India, DR is also used in the food industry and as an ornamental. DR products are used for anti-viral, anti-inflammatory, bronchodilatory, antioxidative, hypnotic, anti-convulsant, laxative, anti-diabetic, anti-microbial, anti-cancer, anti-depressant, neuroprotective, cardioprotective, and hepatoprotective effects as well as pain relief. Clinical trials (CTs) have investigated DR's effects in aromatherapy (AT) by inhalation, vapor diffusion, or massage ("aroma-massage"), with varying results. Narrative and systematic reviews (SRs) also drew differing conclusions. In an SR of herbs in post-surgical pain, oral DR and ginger (Zingiber officinale, Zingiberaceae) caused a nonsignificant reduction in use of rescue medications vs. placebo (PL). In an SR of in vitro, in vivo, and clinical trials, DR was found to have promising analgesic effects in oral, inhaled, or massage forms. An SR of randomized controlled CTs (RCTs) found DR essential oil (EO) in aroma-massage effective in several pain conditions.
This is the first SR and meta-analysis (MA) of RCTs of DR AT used in any manner for acute pain in adults. Electronic databases searched in April and August 2020 yielded 1392 potentially relevant records. References of eligible RCTs and earlier SRs yielded 13, for a total of 1407. Removing 409 duplicates left 918 screened by title and abstract. Of those, 891 were excluded; 27, reviewed in full text. Eleven did not meet SR criteria. Sixteen are included in the SR; 15, the MA. Eligible RCTs compared DR AT to PL, no treatment, or conventional analgesics, and used visual analog or other validated pain scales as their primary outcome and analgesic use secondary. Studies were excluded that used oral or topical DR or combined with another Rosa spp., aromatic, or herb.
Of 16 studies in the SR, 14 were conducted in Iran; two, in Turkey. Fifteen had parallel group designs; one, factorial. Two had four arms; seven, three; and seven, two.* There were 555 participants in DR and 553 in control (CO) arms. Participants had experienced menstrual, burn dressing, labor, post-operative, or renal colic-induced flank pain. DR was administered by inhalation in 12 RCTs; vapor diffusion, three; aroma-massage, one. Products used included DR EO in 10 RCTs, rose water in four, and rose essence in two. [Note: The authors use the term “essence”, so it is impossible to determine if the product was a distillation, infusion, isolate, etc.] AT duration was six – 100 minutes in doses of 0.1 – 1.0 mL. Three studies used routine care as CO; 13, routine care plus PL administered in the same manner as DR. PLs used included almond (Prunus dulcis, Rosaceae) oil, sugar water, and saline solution. Just two studies reported adverse effects (AEs). One study, not included in MA, measured pain only after the intervention. All others had baseline and post-intervention data.
For the MA, baseline and final post-treatment pain scores were pooled to calculate mean changes and standard deviations in DR and CO groups. In 15 studies, 0 – 10-pt. pain scales were used; in one, the 0 – 3-pt. Premenstrual Screening Symptoms Tool (PSST) data were converted to 0 – 10-pt. values and a sensitivity analysis was conducted for that study; results did not alter. Effect sizes are presented as weighted mean differences with 95% confidence interval and P < 0.05 considered statistically significant. DR AT significantly reduced pain severity vs. CO/PL (P< 0.001). Subgroup analyses confirmed this for inhalation AT (P < 0.001) and aroma-massage (P < 0.001) but not vapor diffusion (P = 0.068). There was significant heterogeneity among studies in the main analysis (I2 = 98.2%), inhalation subgroup (I2 = 98.4%), and vapor diffusion subgroup (I2 = 98.4%; P < 0.001 for all). Many sources of heterogeneity are identified but may not be inclusive of all potential sources. Overall, there was more pain reduction, especially of post-operative pain, with AT given for ≥ 30 minutes, at dosages ≥ 0.5 mL and concentrations ≥ 10.0%.
Risks of bias were assessed using the Cochrane tool. The domain "other potential sources of bias" was used to rate inclusion/exclusion criteria, appropriateness of sample size calculation method, funding source declaration, ethical criteria, protocol registration, and conflict of interest declaration. Four RCTs rated as having good quality had low risk of bias in all seven Cochrane domains; seven, rated as fair, high risk in one domain or unclear risk in one or two; five, rated as poor, high risk in one or two domains and unclear risk in > two. Unclear allocation concealment (selection bias) was seen in 10. Blinding (performance), selective reporting (reporting), and other sources of potential bias were the most common high-risk defects. Quality of evidence was low according to Grading of Recommendations of Assessment, Development, and Evaluation standards, used to assess evidence as having high, moderate, low, or very low quality based on five factors. The failure of most RCTs to report on AEs is concerning. No evidence of publication bias was found by Egger's regression (P = 0.333) or visual inspection of funnel plots. Results were not influenced by any single study.
This report augments earlier narrative reviews and SRs. Mechanisms of analgesic action proposed for DR include olfactory stimulation, increased parasympathetic activity, neurotransmitter release, and release of cortisol and noradrenalin. DR's scent may distract patients from pain; this may be related to its reported hypnotic effect. It contains bioactive flavonoids, glycosides, terpenes, and anthocyanins and compounds with pain-relieving effects, e.g., nonadecane, beta-citronellol, henicosane, geraniol, and docosane. Quercetin and kaempferol may also account for its analgesic effects. One of this report's "remarkable" findings is "the paucity of well-designed trials," with only 25% of RCTs having good quality by Cochrane standards and under half, fair. Higher quality RCTs are needed to reliably understand DR's pain-relieving potential in AT and in topical or oral forms. Use of non-Iranian populations would boost generalizability of results.
*For studies with > two arms, data for DR and CO/PL groups were use; for those with both PL and CO groups, PL group were the comparator.