This was a randomized controlled trial with a repeated-measures sham-group design and was conducted between April and November 2013. A flow diagram of the study procedure is presented in Fig. 1, according to the CONSORT statement [36]. The controlled trial was registered with the ClinicalTrials.gov (Reg. No: NCT02187640).
In the absence of previous similar research on acupressure for constipation in psychiatric patients, the sample size calculation was based on Cohen’s standard medium effect size (f = 0.40 with 80 % power at 5 % alpha level) for healthcare and behavioral studies [37], taking into account an expected 20 % attrition rate [28–30]. It was calculated that 39 participants per group (78 participants in total) would be required for analysis of variance tests on the main study outcomes (symptom severity and quality of life), as calculated with G*Power version 3.13 (free download from MacUpdate at http://www.macupdate.com/apps). Seventy-eight eligible adult psychiatric patients volunteered to participate in this study. These patients were recruited over 6 months from five adult psychiatric wards in one 1000-bed regional mental hospital in Hong Kong. A few patients (n = 6) refused to participate, or were not selected because of lack of interest in participating or time constraints. Participants had been admitted to the hospital for acute psychiatric treatment (e.g., psychotropic medication) and rehabilitation before discharge.
Criteria for participation in this study included being: (1) Hong Kong Chinese residents, aged between 18 and 64; (2) willing and mentally competent to learn about, and engage in, self-care and acupressure, as assessed and recommended by the attending psychiatrists; and (3) diagnosed with constipation under the Rome III diagnostic criteria [38]. In relation to these criteria, participants must have presented in the past 6 months with the following symptoms of constipation: (a) rarely having loose stools without the use of laxatives, (b) insufficient evidence of irritable bowel syndrome, and (c) any two or more of the following cardinal symptoms:
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Straining at defecation at least a quarter of the time,
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Lumpy and/or hard stools at least a quarter of the time,
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A sensation of incomplete evacuation at least a quarter of the time,
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A sensation of anorectal obstruction/blockage at least a quarter of the time,
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Manual maneuvers to facilitate defecation at least a quarter of the time, and/or,
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Three or fewer defecations per week.
Participants with the following symptoms were excluded: (1) mental instability over the past month as indicated by their attending psychiatrist; (2) anatomical and physiological disorders of the gastrointestinal tract, such as mal-rotation, fistula, and colonic neuropathies; (3) various comorbidities of mental illness such as metabolic and endocrine diseases, lead poisoning, and vitamin D intoxication; (4) previous training in acupressure; and (5) physical disability involving the upper limbs or pregnancy.
The attending psychiatrist assessed and confirmed whether each participant was mentally competent to participate and whether they understood the instructions for the intervention and the responses to the outcome questionnaires. Informed written consent (Additional file 2) was obtained from participants judged competent to take part in the study. These participants were asked to complete baseline measures of socio-demographic characteristics and study outcomes. Participants were then matched in pairs according to gender, a factor associated with symptom severity and quality of life in previous studies on psychiatric patients with constipation [3, 14, 22]. Two sets of matched pairs of participants were listed and the paired participants in one list were then randomly assigned to either the self-administered acupressure or sham group using computer-generated random number sequences; their matched pairs were assigned to the corresponding study group. Participants in the sham group received similar training and implemented a similar acupressure procedure to the acupressure group, except that they were taught to use sham acupoints and perform abdominal massage with light pressure. Participants in this group were offered acupressure training and supervised practice after the study if the intervention was effective.
Training in self-administered acupressure for relieving constipation was performed according to a standard guideline or protocol for practice [39, 40]. This consisted of two simple procedures, as follows: first, the participant was taught to use the Acupen, a device used to apply constant pressure of 29.5–40.0 newton force onto five acupoints, lasting for approximately 1 min. The five acupoints were Zhongwan (RN12), which is located on the upper abdomen and on the anterior midline 4 cun (just over 10 cm) above the center of the umbilicus [29]; the right and left Tianshu (ST25), located in the central abdominal region and 2 cun (just over 5 cm) lateral to the umbilicus [39]; and the right and left Quchi (LI11), located at the lateral end of the transverse elbow crease when the forearm is flexed and at the midpoint of the line connecting Chize (LU5) to the lateral epicondyle of the humerus [41]. Participants were informed of the specific sensations (e.g., soreness and relaxation) that should be experienced when pressure is applied accurately to the acupoints. Second, gentle rubs (with the palm) with pressure on the abdomen in clockwise circular movements around 2 cun from the umbilicus were performed for another 8 min [42]. The positions of the acupoints and use of the Acupen were illustrated with colored photographs and pictures for the participants’ easy reference. The acupressure and abdominal massage were performed once a day for 10 days in a group setting, supervised by a trained psychiatric nurse and preferably at least 2 h after a meal. The main procedure and features of the acupressure intervention are summarized (in Additional file 3), according to the Standards for Reporting Interventions in Clinical Trials of Acupuncture (STRICTA).
The sham group was trained to perform acupressure in a similar way to the intervention group, except that they used five sham acupoints and mild abdominal massage with slight pressure only. Participants in the sham group were not told about the sensations (e.g., soreness and relaxation) induced by acupressure on the real acupoints. The acupressure and sham group programs were reviewed and agreed upon by a panel of six Chinese medical practitioners and acupressure therapists; minor amendments were made to a few terms about acupoints and the administration of acupressure in the programs.
A training workshop was conducted by an experienced Chinese medical practitioner who had practiced acupressure for 10 years. The workshop was designed to equip five mental health nurses (one in each psychiatric ward under study) with acupressure, abdominal massage, and group supervision skills. The trained nurses were then supervised to teach a group of patients about acupressure until the practitioner was satisfied with and confirmed their competence to train their patients in acupressure with the aid of a manual for self-administered acupressure. Each of the nurses also practiced training a group of four patients in self-administered acupressure under the supervision of the practitioner prior to the start of the study interventions. The treatment fidelity among the five trained nurses was confirmed by the research team according to the items in the treatment manual, and their performance was found to be 93–98 % accurate for all items.
Instruments
A socio-demographic and clinical data sheet (Additional file 4) was completed at baseline. The primary and secondary outcome measures were scores on the Chinese versions of the CAS and the PAC-QoL questionnaire, respectively. These outcome measures were administered by the researcher (who was blind to participants’ group assignment) at recruitment, immediately after the 10-day interventions, and 2 weeks after the interventions.
The 8-item CAS has been frequently used to assess constipation symptoms in the previous 7 days, such as abdominal distention or bloating, frequency of bowel movements, oozing of liquid stool, and rectal pain with bowel movements. Subjects were asked to rate each item on a 3-point Likert scale: 0 = no problem, 1 = some problems, and 2 = severe problems. Higher total scores (possible range 0–16) indicate more severe constipation symptoms.
The 28-item PAC-QoL consists of four subscales: satisfaction with constipation symptoms and treatment (five items), physical discomfort (four items), psychosocial discomfort (eight items), and worries and concerns (11 items) [35]. Items are rated on a five-point Likert scale, ranging from 0 = none of the time or not at all to 4 = all of the time or extremely. The total and subscale scores were averaged by the total number of items, and then each average score (ranging from 0 to 4) was used for comparison. The lower the average total and subscale scores, the better the person’s perceived health-related quality of life.
Data analysis
Descriptive statistics (frequency and mean [standard deviation]) were used to describe the socio-demographic data and scores on the outcome variables (PAC-QoL and CAS). The homogeneity of the two study groups was assessed by comparing their baseline outcome scores and socio-demographic characteristics using the Chi-square test (for nominal variables) and the independent sample t test or Mann–Whitney U test (for continuous variables). The mean scores of the two outcome variables were not normally distributed and there were significant differences in PAC-QoL mean scores between groups at the baseline. Therefore, the generalized estimating equation (GEE) test was used to compare differences in CAS and PAC-QoL mean scores between the treatment and sham groups across time (pretest and two post-tests), followed by contrast tests. For outcome measures showing significant results in the GEE test, subgroup analyses were performed to examine any significant differences in mean scores between subgroups for gender, age, type of antipsychotic drug used, use of laxatives, and tendency to suppress defecation. The level of significance for all statistical tests was set at 0.05.
Ethical approval (NTW-2012-0009) and permission to conduct the study were obtained from the Human Subjects Research Ethics Committee at The Hong Kong Polytechnic University and the Clinical Research Ethics Committee of the Hospital Authority, Hong Kong. The aim and procedure of the study were explained to the participants who met the study criteria and those who agreed to participate provided written consent.