PubMed.gov: Meta-Analysis Sci Rep. 2018 Nov 2;8(1):16252. doi: 10.1038/s41598-018-34303-z.
By: Junyoung Jo and Sun Haeng Lee
Abstract
Primary dysmenorrhea, which is menstrual pain without pelvic pathology, is the most common gynecologic condition in women. Heat therapy has been used as a treatment. We assessed the evidence on heat therapy as a treatment for primary dysmenorrhea. We searched 11 databases for studies published through July 2018. All randomized controlled trials (RCTs) that addressed heat therapy for patients with primary dysmenorrhea were included. Data extraction and risk-of-bias assessments were performed by two independent reviewers. Risk of bias was assessed using the Cochrane risk-of-bias tool. Six RCTs met our inclusion criteria. Two RCTs found favorable effects of heat therapy on menstrual pain compared with unheated placebo therapy. Three RCTs found favorable effects of heating pads on menstrual pain compared with analgesic medication (n = 274; SMD −0.72; 95% confidence interval −0.97 to −0.48; P < 0.001; two studies). One RCT showed beneficial effects of heat therapy on menstrual pain compared with no treatment (n = 132; MD −4.04 VAS; 95% CI −4.88 to −3.20; P < 0.001). However, these results are based on relatively few trials with small sample sizes. Our review provided suggestive evidence of the effectiveness of heat therapy for primary dysmenorrhea, but rigorous high-quality trials are still needed to provide robust evidence
Introduction
Primary dysmenorrhea refers to painful menstrual cramps in the lower abdominal region during menstruation in the absence of any discernible macroscopic pelvic pathology1. It frequently involves other symptoms, including sweating, headache, nausea, vomiting, diarrhea, and tremulousness before or during menstration2. Its estimated prevalence varies between 45% and 95% of all women of reproductive age3. Dysmenorrheic pain is the primary cause of recurrent short-term school or work absenteeism among young women of childbearing age4. Women with this condition report that menstruation has an immediate negative impact on their quality of life (QoL), whereas women who do not suffer from this condition do not report such an experience during menstruation4. Pelvic pain may also cause anxiety and depression, which can amplify the severity of pain5–7. Despite its negative effects and the availability of treatment at minimal cost, few patients with primary dysmenorrhea visit medical clinics, and members of this population are frequently undertreated8,9.
Nonsteroidal anti-inflammatory drugs (NSAIDs) are considered the primary treatment for primary dysmenorrhea, but they commonly cause adverse effects (AEs), including indigestion, headaches, and drowsiness10. Typically, hormone contraceptives are used only for women who are not planning to become pregnant9. Therefore, many women also seek alternative therapies, such as heating pads for cramps, to manage their menstrual discomfort4,11. A recent systematic review suggested that heat therapy may be related to pain reduction, although rigorous high-quality trials are still needed before conclusive recommendations can be made11. However, as the review did not include several important randomized controlled trials (RCTs), another comprehensive review that focuses on the type and method of various heating modalities is needed.
Superficial heat that ranges from 40–45 °C treats the application site to a depth of about 1 cm. Traditionally, superficial heat has been used in different forms (e.g., hot water bags, towels, or bottles) to ease menstrual pain. Although deep heat, such as shortwave diathermy and microwave diathermy, treats deeper structures at depths of 2–5 cm, deep heat also causes vascular and metabolic changes in deeper tissues and organs12. Studies have found that heat is a common (36.5–50%) method for coping with dysmenorrhea13. For women with dysmenorrhea, the application of local heat can reduce muscle tension and relax abdominal muscles to reduce pain caused by muscle spasms. Heat can also increase pelvic blood circulation to eliminate local blood and body fluid retention and diminish congestion and swelling, thereby enabling a reduction in pain caused by nerve compression14. Therefore, in this review, we investigated current evidence related to the effectiveness of heat therapy as a treatment for primary dysmenorrhea. All RCTs dealing with heat therapy for patients with primary dysmenorrhea were analyzed to compare the effects of this treatment with those of control treatments on pain indicators.
Results
Description of included trials
After removing duplicates, 1052 studies were screened and 15 full-text articles were assessed for eligibility. Three studies that used moxibustion were excluded because it delivers heat and excites the nervous system by acupoint stimulation15. Two observational studies, one summary, and one trial protocol were also excluded. One study compared infrared heat to hot packs, and the other study was conducted in a non-randomized setting. Therefore, six RCTs were ultimately included in the analysis (Fig. 1). The characteristics of the included studies are summarized in Table 1. Two RCTs were conducted in America16,17, and one RCT each was conducted in Iran18, Korea19, Taiwan14, and Turkey13. All of the studies were published in peer-reviewed journals. Four studies used a heating device, such as a patch or wrap13,16–18, and two studies used a ceramic belt emitting far-infrared radiation (FIR)14,19. Details of the heat treatment are listed in Table 2. Akin et al. (2001 and 2004) reported only the mean value17 or the mean value and standard error of the reduction in pain scores16. Furthermore, the exact number of participants in the intervention and control groups was unclear. Akin et al. (2004) reported that 357 participants finished the trial, and 11 participants were excluded; however, they finally analyzed 344 participants16. Ke et al. just reported pain scores using figures with no numerical values14. One of the authors (JJ) contacted the corresponding authors by electronic mail to request additional information, but the authors replied either that they had no raw data16,17 or did not respond14. Therefore, meta-analyses were performed using the other two studies that compared a heat patch with an analgesic13,18. Another study that compared the FIR belt with a heat pack with a placebo belt with a heat pack was reported separately19. We used data from the first menstrual cycle after treatment, with the exception of one study, which reported a baseline difference in pain intensity during the first menstrual cycle13.
Discussion
This systematic review, which included six studies, found that heat therapy appears to decrease menstrual pain in women with primary dysmenorrhea. There was a consistent reduction in menstrual pain with heat therapy compared with unheated placebo therapy. There was also a trend towards a reduction in menstrual pain with heat therapy compared with analgesic drugs. These results appear promising but should be interpreted cautiously because they are based on relatively few trials with an unclear risk of selection bias.
We included only RCTs to remove potential bias and did not have any language restrictions. Although our literature searches included English and Korean databases, and also included searching by hand for relevant articles, we cannot be absolutely certain that all relevant RCTs were found. The meta-analysis included small numbers of studies with relatively small sample sizes. This contributed to imprecision in estimates. There were variations in the duration, type of heat therapy (e.g. patch or wrap or ceramic belt emitting FIR), and duration of follow up used in these studies, leading to heterogeneity in the findings. Akin et al. reported only the mean value17 or the mean value and standard error of the reduction in pain outcomes16. Ke et al. reported the outcome only in figures in the paper14; therefore, meta-analyses were available from only two studies. A recently published review, which examined the same topic as this article11, included a non-RCT that was excluded from our review. Additionally, it failed to include several important studies16,17,19 that were included and analyzed in our review.
NSAIDs appear to be an effective treatment for dysmenorrhea, although women using them need to be aware of the substantial risk for AEs10. Hormone contraceptives are available only for patients who do not plan to become pregnant9. Our systematic review showed the clear benefit of heat therapy for menstrual pain in women with primary dysmenorrhea. Whether this translates into long-term clinical benefits has yet to be demonstrated. One argument for using heat therapy for the management of dysmenorrhea may be that it causes fewer AEs than conventional drugs. However, there was no evidence that there is a difference among them with regard to AEs. If heat therapy were effective and safe for the management of dysmenorrhea in both the short- and long-term, it could become a first-line non-pharmacologic treatment to decrease menstrual pain in women with primary dysmenorrhea, particularly those with contraindications for NSAIDs.
This systematic review and meta-analysis suggests that heat therapy was associated with a decrease in menstrual pain in women with primary dysmenorrhea. These results are consistent with the recommendation of local heat as a complementary treatment for dysmenorrhea9. We need to compare the effects of various heating modalities with those of other general interventions in terms of short- and long-term outcomes as well as cost-effectiveness. A well-designed multicenter trial to address this issue and provide robust evidence of benefit is warranted to clarify the role of heat therapy in this population.
Source:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6214933/
