In total 121 women, 13-40 years old, with diagnosed endometriosis stage I-IV according to the American Society for Reproductive Medicine, were included in the studies for acupuncture treatment of their endometriosis-related pain (Table 1).
In all three studies, the patient-rated pain intensity was the primary outcome variable, although evaluated with the use of different uni-dimensional rating scales (Visual Analog Scale, Numeric Rating Scale, and Verbal Rating Scale). In two of the studies, patients pain intensity was rated on the scale's upper half before the start of the treatment, while the patients' pain intensity ratings, in the study by Wayne et al, was spread from the lower part of the scale to its upper. The women also rated their health-related quality of life (HRQOL) in two of the studies with different multidimensional instruments (SF-36, Endometriosis Health Profile-30, and The Paediatric Quality of Life Inventory). Additional outcome variables in the study of Rubi-Klein et al were rated pain disability, patients' treatment expectation, take home baby rate, number of absent days, and analgesic intakes. Wayne et al additionally asked their patients to rate their perceived symptom severity by their perceived stress. Also, the presence of serum inflammatory markers was measured in the same study. In the retrospective case series study by Highfield et al, the two adolescent girls also responded to questions on the symptom of the greatest concern, eg, fatigue, constipation, medication, and attendance at school. Description of assessment instruments and time-point for assessment are described in Table 1.
Methodological aspects of the treatment procedures that are described by items in the checklist according to STRICTA are presented in Table 2. Two of the studies used acupuncture techniques based on traditional Chinese medicine and Japanese acupuncture technique, all individually tailor based on the patient's symptoms.
The selection of acupuncture points varied between the studies, but they were in summary anatomically located in the lower back/pelvic region, in the lower abdominal area, and also in the hands and feet. The points were intra segmentally related to visceral organ innervation. One of the studies also described the additional use of auricular acupuncture points.
Stimulation depth in the three studies varied from being intracutaneous and subcutaneous to being intramuscular. The stimulation was mainly manual but with different intensity characterized by a needle sensation, deQi, in the studies of Highfield et al and Rubi-Klein et al, while a sensation described as weaker or more gentle than the deQi sensation and characterized as an "echo" in the therapist's hand was sought for in the study by Wayne et al. Moxa applied on the needles were described in all three studies as a possibility when regarded as appropriate.
The needle insertions per subject and treatment session were 7-12, and the needle retention time described as 15-20 minutes. The number of treatments varied from 9 to 16 among the three studies and the treatment frequency was presented as twice a week in works by Wayne et al and Rubi-Klein et al, while Highfield et al described that as in average a little bit more than once a week. Continuation with the regular analgesic intervention was reported in two of the studies.
Two of the three studies were aimed to evaluate the efficacy of acupuncture as compared to a control group. As a control method, Rubi-Klein et al used non-specific acupuncture points (ie, well-defined acupuncture points according to traditional Chinese medicine principles are unrelated to endometriosis) that in this case were located on the head, shoulder, chest, and thigh. The non-specific acupuncture points were stimulated less, described as a constant subcutaneous neutral needling technique, as compared to the "real" acupuncture technique where a needling sensation often in intramuscular tissue was sought for. This study also had a crossover design, meaning that the groups changed the type of treatment. Wayne et al used the non-penetrating Streitberger needles as a control treatment where these needles were attached to the skin over non-acupuncture points close to (1 cm away) defined acupuncture points in the forearm, shank, and foot. The treatments were performed at a hospital, in the acupuncturist's office, or in the patient's home.
The first two studies reported a dropout among their patients, 18 and four patients respectively, resulting in a total of 99 women who were included in the analysis of treatment effects, as shown in Table 3.
In all three studies, the patients rated their pain intensity lower after acupuncture treatment, regardless of the acupuncture technique, as compared to before the start of the treatment period. Another aspect of pain evaluation, rated pain disability, used by Rubi-Klein et al was rated lower after treatment.
Also, the treated patient rated their HRQOL higher in two of studies. Decrease of analgesic intake and perceived stress within the acupuncture-treated groups were reported in the studies of Rubi-Klein et al and Wayne et al, respectively. In the observational study by Highfield et al, the social activity and attendance in school activity were reported as increased after the treatment period.
Systematic differences between the treatment group and the control group in the evaluation of rated pain intensity and the HRQOL subgroups "social efficiency" and "psychological well-being" were demonstrated in the Rubi-Klein et al study. A long-lasting effect of acupuncture on perceived pain in the same study made it difficult to interpret the effect of control treatment after being giving the "real" acupuncture.
In the study by Wayne et al, there were also some effects reported but there was not enough evidence to establish systematic differences between the groups in any of the used outcome variables.