A randomised clinical trial of the effect of informed consent on the analgesic activity of placebo and naproxen in cancer pain. Does informed consent influence therapeutic outcome? A clinical trial of the hypnotic activity of placebo in patients admitted to hospital. Dynamics and significance of placebo response in primary dysmenorrhea. Double-blind, placebo-controlled trial of famotidine in children with abdominal pain and dyspepsia: global and quantitative assessment. Is recruitment more difficult with a placebo arm in randomised controlled trials? A quasirandomised, interview based study. Patient participation in the patient-provider interaction: the effects of patient question asking on the quality of interaction, satisfaction and compliance. Effect and placebo effect of acupressure (P6) on nausea and vomiting after outpatient gynaecological surgery. The use of analgesics in patients with acute abdominal pain. Randomized controlled trial of Gastrografin in adhesive small bowel obstruction.
To determine whether informed consent in a therapeutic trial modifies the analgesic effect of naproxen and placebo, we conducted a prospective, randomised, single dose, placebo-controlled trial. Patients were randomly selected to receive or not information concerning the study. All patients included were then given a single dose of naproxen and placebo according to a crossover, double-blind design. Forty-nine patients with mild or moderate cancer pain which did not need narcotic analgesics entered the study. Twenty-five received both treatments without any information and constituted the uninformed group. Twenty-four had a complete information about the trial; six refused to participate. The 18 others constituted the informed-consent group. Visual analogue scales of pain before and 30, 60, 120 and 180 min after the intake of naproxen and placebo were recorded. As an analgesic, naproxen was more effective than placebo in both groups of patients (p = 0.001). For naproxen as well as for placebo, the analgesic effect was better in the informed-consent group compared to the uninformed group (p = 0.012). The difference in therapeutic activity between naproxen and placebo was moderately higher in the uninformed patients (p = 0.08). We concluded that, in contrast with parallel studies, giving information in a crossover, placebo-controlled trial may increase the apparent efficacy of both the tested agent and the placebo, and decrease the perceived difference the two. To examine whether written informed consent might influence the results of clinical trials the effect of placebo when given with or without informed consent to patients suffering from insomnia was studied. The study was a single blind observer blinded trial, and patients were paired according to sex, age, and hospital environment. Randomisation assigned the first patient of each pair to the control group (without informed consent) or the group to give informed consent. Of the 56 patients, 26 refused to give informed consent, and the age and sex distribution of these differed significantly (p less than 0.02) from the 30 pairs of patients ultimately enrolled into the study. In this "biased" sample, the hypnotic activity of placebo was significantly higher in the control group (p less than 0.05). It is concluded that the informed consent procedure biases the results of clinical trials and might affect their general applicability. A total of 55 patients with primary dysmenorrhea who had shown a favorable response to a preliminary treatment cycle with placebo were admitted to a double-blind study on placebo versus antiprostaglandin agents (naproxen and pirprofen). To evaluate the placebo effect and its duration, the treatment was given for 4 successive cycles. Whereas the antiprostaglandin agents were effective in most of the patients (in 80% of the pirprofen group and 85.7% of the naproxen group) and this efficacy was maintained throughout the study, a favorable response to placebo was observed in 84% in the first cycle, 29% in the second, 16% in the third and 10% in the fourth. The incidence of side effects was similar in the placebo and the active treatment groups (35.4% vs. 37.5%). It is postulated that a placebo effect in dysmenorrhea is due to a central analgesic mechanism mediated by endorphin release or possibly to psychological dynamics (mental or conditioning theories). However, this effect loses efficacy with time possibly due to a decreased susceptibility to the opioid action of the central nervous circuits responsible for menstrual pain perception or to deconditioning mechanisms. To determine the benefit of using an H2-receptor antagonist in children with abdominal pain and dyspepsia, 25 such children were enrolled in a double-blind, placebo-controlled trial of famotidine. Global and quantitative pain assessments were done before and after each treatment period. The quantitative assessment was calculated based on the abdominal pain score that was the sum of three components. Based on the global evaluation, there was a clear benefit of famotidine over placebo (68% vs 12%). Using the quantitative assessment, however, the mean improvement of the score using famotidine versus placebo was not statistically significant (3.37+/-3.53 vs 1.66+/-2.7). There was a significant improvement in this score during the first treatment period regardless of medication used (period effect: P = 0.05). A subset of patients with peptic symptoms demonstrated a significant drug effect that outweighed the period effect (drug effect: P = 0.01; period effect: P = 0.02). We conclude that famotidine subjectively improves the symptoms of children with recurrent abdominal pain but not objectively using the derived score. However, famotidine is significantly more effective than placebo among children with peptic symptoms. The use of this simple scoring scale may facilitate selecting those children who will benefit from H2-receptor antagonist therapy. To investigate whether including a placebo arm in a clinical trial of hormone replacement therapy influenced women's stated willingness to participate.
                Quasirandomised, interview based study. Setting: 10 group practices in the Medical Research Council's General Practice Research Framework.
                436 postmenopausal women aged 45-64 who had not had a hysterectomy.
                Stated willingness to enter a trial and reasons for the decisions made.
                Of 218 women told about the trial without a placebo arm, 85 (39%) indicated their willingness to enter compared with 65 (30%) of the 218 women told about the trial with the placebo arm (P=0.06). Part of this difference was due to explicit reluctance to take a placebo. Altruism and personal benefit were the reasons most frequently given for wanting to take part in a trial. The reasons most frequently cited for not wanting to take part were reluctance to restart periods, not wanting to take unknown or unnecessary tablets, or not wanting to interfere with present good health.
                For preventive trials the inclusion of a placebo arm may reduce patients' willingness to participate. The purpose of this study was to investigate the effectiveness, dynamics, and consequences of a health education intervention designed to increase patient question asking during the patient's medical visit. Data were collected at a Baltimore family and community health center which provides outpatient services to a low income, predominantly black and female population. The majority of the study participants were, in addition, elderly and chronically ill. A total of 294 patients and 3 providers took part in the study. The study design included random assignment of patients to experimental and placebo groups with two non-equivalent (non-randomized) control groups. Findings included: (1) The experimental group patients asked more direct questions and fewer indirect questions than did placebo group patients. (2) The experimental group patient-provider interaction was characterized by negative affect, anxiety, and anger, while the placebo group patient-provider interaction was characterized as mutually sympathetic. (3) The experimental group patients were less satisfied with care received in the clinic on the day of their visit than were placebo patients. (4) The experimental group patients demonstrated higher appointment-keeping ratios (an average number of appointments kept divided by an average number of appointments made) during a four-month prospective monitoring period. Acupuncture and acupressure have previously been reported to possess antiemetic effect. We wanted to investigate the "true" and placebo effect of acupressure in prevention of postoperative nausea and vomiting (PONV).
                Sixty women undergoing outpatient minor gynaecological surgery were entered into a double-blind and randomised study. One group received acupressure with bilateral stimulation of P6 (A), a second group received bilateral placebo stimulation (P) and a third group received no acupressure wrist band and served as a reference group (R). PONV was evaluated as number of patients with complete response (no PONV), nausea only or vomiting. In addition, the need for rescue antiemetic medication and nausea after 24 h was registered.
                Complete response was obtained in 11, 11 and 9 patients in groups, A, P and R, respectively. Nine, 7 and 6 patients had nausea before discharge home, and 1, 1 and 8 patients were nauseated (8 vs 1 patient: P < 0.05) 24 h after operation in A, P and R groups, respectively. When compared to placebo acupressure (2 patients vomited and 5 needed rescue), significantly (P < 0.05) fewer needed rescue antiemetic medication after acupressure at P6 (no vomiting or rescue medication). When compared to the observation group (5 vomited and 4 needed rescue antiemetics), significantly fewer vomited after acupressure (P < 0.05)
                In patients undergoing brief gynaecological surgery, placebo effect of acupressure decreased nausea after 24 h but vomiting and need of rescue antiemetics was reduced only by acupressure with the correct P6 point stimulation. Analgesics in patients with acute abdominal pain are often withheld for fear that they may change physical examination findings and thus may be unsafe. We conducted a randomized, prospective, placebo-controlled trial to investigate changes in physical examination following the administration of placebo, 5 mg, or 10 mg of morphine to 49 patients with acute abdominal pain. One patient was withdrawn secondary to inadequate documentation. Of the 48 patients who completed the trial, a statistically significant change in physical examination was noted in both groups receiving analgesics, but not in the placebo group. No adverse events or delays in diagnosis were attributed to the administration of analgesics. We conclude that physical examination does change after the administration of analgesics in patients with acute abdominal pain and that a larger study is needed to evaluate analgesic safety in this subpopulation of emergency department patients. Several previous studies have shown that Gastrografin can be utilized to triage patients with adhesive small bowel obstruction (ASBO) to an operative or a non-operative course. Previous studies assessing the therapeutic effect of Gastrografin have been confounded by post-administration radiology alerting the physician to the treatment group of the patient. Therefore the aim of the present paper was to test the hypothesis that Gastrografin hastens the non-operative resolution of (ASBO).
                Patients, diagnosed with ASBO on clinical and radiological grounds, were randomized to receive Gastrografin or placebo in a double-blinded fashion. Patients did not undergo further radiological investigation. If the patient required subsequent radiological intervention or surgical intervention they were excluded from the study. End-points were passage of time to resolution of ASBO (flatus and bowel motion), length of hospital stay and complications.
                Forty-five patients with ASBO were randomized to receive either Gastrografin or placebo. Two patients were excluded due to protocol violations. Four patients in each group required surgery. Eighteen of the remaining patients received Gastrografin and 17 received placebo. Patients who received Gastrografin had complete resolution of their ASBO significantly earlier than placebo patients (12 vs 21 h, P = 0.009) and this translated into a median of a 1-day saving in time in hospital (3 vs 4 days, P = 0.03).
                Gastrografin accelerates resolution of ASBO by a specific therapeutic effect.
We did not find that placebo interventions have important clinical effects in general. However, in certain settings placebo interventions can influence patient-reported outcomes, especially pain and nausea, though it is difficult to distinguish patient-reported effects of placebo from biased reporting. The effect on pain varied, even among trials with low risk of bias, from negligible to clinically important. Variations in the effect of placebo were partly explained by variations in how trials were conducted and how patients were informed.