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Biomedical subjects

H McQuay

Publications and source records attributed to H McQuay.

At least 37 records · Page 2Linked to original sources
PubMed1996

Deriving dichotomous outcome measures from continuous data in randomised controlled trials of analgesics.

Reports of RCTs of analgesics frequently describe results of studies in the form of mean derived indices, rather than using discontinuous events--such as number or proportion of patients with 50% pain relief. Because mean data inadequately describe information with a non-normal distribution, combining mean data in systematic reviews may compromise the results. Showing that dichotomous data can reliably be derived from mean data, at least in acute pain models, indicates that more meaningful overviews or meta-analysis may be possible. This study investigated the relationship between continuous and dichotomous analgesic measures in a set of individual patient data, and then used that relationship to derive dichotomous from continuous information in randomised controlled trials (RCTs) of analgesics. Individual patient information from 13 RCTs of parallel-group and crossover design in acute postoperative pain was used to calculate the percentage of the maximum possible pain relief score (%maxTOTPAR) and the proportion of patients with greater than 50% pain relief (> 50%maxTOTPAR) for the different treatments. The relationship between the measures was investigated in 45 actual treatments and 10,000 treatments simulated using the underlying actual distribution; 1283 patients had 45 separate treatments. Mean %maxTOTPAR correlated with the proportion of patients with > 50%maxTOTPAR (r2 = 0.90). The relationship calculated from all the 45 treatments predicted to within three patients the number of patients with more than 50% pain relief in 42 of 45 treatments, and 98.8% of 10,000 simulated treatments. For seven effective treatments, actual numbers-needed-to-treat (NNT) to achieve > 50%maxTOTPAR compared with placebo were very similar to those derived from calculated data.

Analgesics↗
PubMed1996

Developing a database of published reports of randomised clinical trials in pain research.

A database of randomised clinical trials (RCTs) in pain research published from 1950 to 1990 was created following an extensive literature search. By applying a refined MEDLINE search strategy from 1966 to 1990 and by hand-searching more than 1,000,000 pages of a total of 40 biomedical journals published during the period 1950-1990, more than 8000 RCTs were identified. The RCTs were published in more than 800 journals and over 85% appeared between 1976 and 1990. If the trend of the last 15 years persists, a total of more than 15 000 RCTs will be published in pain relief by the year 2000. A detailed description of methods to ensure efficient use of resources during the identification, retrieval and management of the information in pain relief and other fields is given. Emphasis is made on the importance of refining MEDLINE search strategies, on the use of volunteers to hand-search journals and on careful monitoring of each of the steps of the process. The potential uses of the database to guide clinical and research decisions are discussed.

Databases, Bibliographic↗
PubMed1996

Omitting nitrous oxide in general anaesthesia: meta-analysis of intraoperative awareness and postoperative emesis in randomized controlled trials.

We have reviewed randomized controlled trials to assess the effectiveness and safety of anaesthetics which omitted nitrous oxide (N2O) to prevent postoperative nausea and vomiting (PONV). Early and late PONV (6 and 48 h after operation, respectively), and adverse effects were evaluated using the numbers-needed-to-treat (NNT) method. In 24 reports with information on 2478 patients, the mean incidence of early and late vomiting with N2O (control) was 17% and 30%, respectively. Omitting N2O significantly reduced vomiting compared with a N2O regimen; the combined NNT to prevent both early and late vomiting with a N2O-free regimen was about 13 (95% confidence intervals (CI) 9, 30). The magnitude of the effect depended on the incidence of vomiting in controls. In studies with a baseline risk higher than the mean of all reports, the NNT to prevent both early and late vomiting with a N2O-free anaesthetic was 5 (95% CI 4, 10). When the baseline risk was lower than the mean, omitting N2O did not improve outcome. Omitting N2O had no effect on complete control of emesis or nausea. The NNT for intraoperative awareness with a N2O-free anaesthetic was 46 compared with anaesthetics where N2O was used. This clinically important risk of major harm reduces the usefulness of omitting N2O to prevent postoperative emesis.

Anesthesia, General↗
PubMed1996

Randomization is important in studies with pain outcomes: systematic review of transcutaneous electrical nerve stimulation in acute postoperative pain.

We set out to examine the evidence for the importance of randomization of transcutaneous electrical nerve stimulation (TENS) in acute postoperative pain. Controlled studies were sought; randomization and analgesic and adverse effect outcomes were summarized. Forty-six reports were identified by searching strategies. Seventeen reports with 786 patients could be regarded unequivocally as randomized controlled trials (RCT) in acute postoperative pain. No meta-analysis was possible. In 15 of 17 RCT, we judged there to be no benefit of TENS compared with placebo. Of the 29 excluded trials, 19 had pain outcomes but were not RCT; in 17 of these 19 TENS studies, the authors concluded that TENS had a positive analgesic effect. No adverse effects were reported. Non-randomized studies overestimated treatment effects.

Acute Disease↗
PubMed1995

Anticonvulsant drugs for management of pain: a systematic review.

OBJECTIVE: To determine effectiveness and adverse effects of anticonvulsant drugs in management of pain. DESIGN: Systematic review of randomised controlled trials of anticonvulsants for acute, chronic, or cancer pain identified by using Medline, by hand searching, by searching reference lists, and by contacting investigators. SUBJECTS: Between 1966 and February 1994, 37 reports were found; 20 reports, of four anticonvulsants, were eligible. MAIN OUTCOME MEASURES: Numbers needed to treat were calculated for effectiveness, adverse effects, and drug related withdrawal from study. RESULTS: The only placebo controlled study in acute pain found no analgesic effect of sodium valproate. For treating trigeminal neuralgia, carbamazepine had a combined number needed to treat of 2.6 for effectiveness, 3.4 for adverse effects, and 24 for severe effects (withdrawal from study). For treating diabetic neuropathy, anticonvulsants had a combined number needed to treat of 2.5 for effectiveness, 3.1 for adverse effects, and 20 for severe effects. For migraine prophylaxis, anticonvulsants had a combined number needed to treat of 1.6 for effectiveness, 2.4 for adverse effects, and 39 for severe effects. Phenytoin had no effect on the irritable bowel syndrome, and carbamazepine had little effect on pain after stroke. Clonazepam was effective in one study for temporomandibular joint dysfunction. No study compared one anticonvulsant with another. CONCLUSIONS: Anticonvulsants were effective for trigeminal neuralgia and diabetic neuropathy and for migraine prophylaxis. Minor adverse effects occurred as often as benefit.

Anticonvulsants↗
PubMed1995

Comparison of the sensitivity to change of long and short form pain measures.

Our objective was to assess the sensitivity to change over time of three methods of assessing pain. We conducted a comparison of the sensitivity to change of three pain assessment measures in a double blind, double dummy parallel group study evaluating the efficacy of one of two doses of oral bromfenac and one of two doses of sublingual buprenorphine. Our subject pool consisted of 75 patients following general surgical and orthopaedic procedures. Pain intensity was measured by the affective, sensory and evaluative dimensions of the McGill Pain Questionnaire together with total score and word score, a 10 cm Visual Analogue Scale and by a four word scale. Effect size calculations indicated considerable variation in the sensitivity of the instruments to change. However, despite variation in the size of effect indicated by different measures, there was consistent agreement as to the most effective treatment regimen. This study suggests that simple measures of pain are sensitive to change and are worthwhile indicators of the impact of an intervention upon acute pain, although some care is needed in interpreting results from such instruments. More complex forms of assessment, such as the calculation of the MPQ sub-scales may not add anything to such data.

Adult↗
PubMed1995

Prevention of vomiting after paediatric strabismus surgery: a systematic review using the numbers-needed-to-treat method.

Randomized controlled studies were reviewed to assess the effectiveness and safety of antiemetics used for prophylaxis in paediatric strabismus surgery. Early and late vomiting (6 and 48 h after operation, respectively), and adverse effects were evaluated using the numbers-needed-to-treat method. In 27 reports with information on 2033 children, the mean incidence of early vomiting was 54% and of late vomiting 59%, without prophylaxis. Only three drugs were studied sufficiently for firm conclusions to be drawn. In the best documented regimen (droperidol 75 micrograms kg-1), four children have to be given the drug to prevent one vomiting; of the three others, one may vomit and two would not have vomited anyway; fewer than one child in 100 may have an extrapyramidal reaction and 16 may have minor adverse effects. Metoclopramide 0.15 and 0.25 mg kg-1 was significantly better than control only for early vomiting. Propofol had a high incidence of oculocardiac reflex without conferring any significant antiemetic effect: it should not be used. The benefits of prophylactic antiemetic therapy are not proven.

Antiemetics↗
PubMed1993

Single-dose, randomized, double-blind, double-dummy cross-over comparison of extradural and i.v. clonidine in chronic pain.

We studied 10 patients with chronic back pain who had claimed benefit with a previous extradural dose of clonidine 150 micrograms combined with local anaesthetic. We compared a single dose of clonidine 150 micrograms given by either the extradural or i.v. route in a double-blind, randomized, double-dummy and cross-over fashion, with 80% power to detect a difference in the analgesic effect of the two routes. Pain intensity, pain relief, adverse effects, mood, sedation and vital signs were assessed by a nurse observer. I.v. clonidine produced significantly (P < 0.04) greater analgesia than extradural clonidine in one of the five analgesic outcome measures. Clonidine given by either route produced statistically significant sedation and significant decreases in arterial pressure and heart rate. In this study, extradural clonidine had no significant clinical advantages compared with i.v. clonidine; clonidine 150 micrograms by either route produced a high incidence of adverse effects.

Adult↗
PubMed1993

Oral bromfenac 10 and 25 mg compared with sublingual buprenorphine 0.2 and 0.4 mg for postoperative pain relief.

The aim of this single-dose, randomized, positive control, double-dummy, double-blind, parallel group study was to compare oral bromfenac 10 and 25 mg with sublingual buprenorphine 0.2 and 0.4 mg for treatment of postoperative pain. We studied 91 patients with moderate or severe pain after general surgical or orthopaedic operations, using pain intensity, pain relief, adverse effect, mood and sedation outcomes. There was a significant analgesic dose-response for buprenorphine, showing study sensitivity, but not for bromfenac. The two bromfenac treatments were significantly superior to the two buprenorphine treatments. Significantly more patients reported nausea with buprenorphine. There was evidence of a ceiling effect for analgesia with bromfenac.

Administration, Oral↗
PubMed1985

Morphine kinetics and kidney transplantation: morphine removal is influenced by renal ischemia.

Morphine plasma concentrations were determined in six patients receiving kidney transplants from living-related donors, and nine patients receiving kidney transplants from cadavers. The total cold ischemic time was about 2 hr for kidneys from living-related donors and 14 hr for those from cadavers. After an intravenous bolus dose of morphine, plasma morphine concentrations decreased to a plateau that lasted for several hours; morphine elimination resumed when the transplanted kidney began to clear creatinine. The duration of the total cold ischemic time was significantly related to both the duration of the plateau in morphine concentration (P = 0.008) and the first postoperative day creatinine clearance (P = 0.021). Morphine elimination half-life after the plateau was related to first postoperative day creatinine clearance (P less than 0.001). It was concluded that morphine elimination depended upon intact renal function.

Adult↗
PubMed1984

Spinal fluid kinetics of morphine and heroin.

Nine patients undergoing cardiopulmonary bypass surgery were given either 2 mg diamorphine or 2.5 mg morphine by intrathecal injection. Spinal fluid (sf) samples were collected over 25 min and drug concentrations measured by HPLC. Concentrations in sf were about 4000 times as great as after 1 mg/kg IV morphine. The kinetic properties of morphine and heroin in sf differed; diamorphine was removed from sf much more rapidly than morphine. Lipophilic opiates may be safer for intrathecal use because of the shorter life of substantial drug concentrations in the mobile sf phase.

Chromatography, High Pressure Liquid↗
PubMed1984

Morphine kinetics during and after renal transplantation.

Plasma concentrations after intravenous morphine were measured by a specific radioimmunoassay method in patients undergoing renal transplantation and in control subjects. In both transplant patients and controls, plasma morphine fell in the first 10 min, but there was no significant further fall in the transplant patients until between 3 and 5 hr, when there was an abrupt reversion to the same elimination t1/2 as the controls. This coincided with recovery of renal function after the period of cold ischemia. In the transplant patients the AUC over 24 hr was higher and the plasma clearance was lower than in controls. The role of the kidney in morphine elimination is discussed.

Adult↗
PubMed1984

Plasma morphine concentrations and analgesic effects of lumbar extradural morphine and heroin.

Patients undergoing lumbar laminectomy were given extradural narcotic, either 5 mg morphine sulphate or 5.5 mg heroin (diamorphine hydrochloride); the extradural catheter had been positioned adjacent to the dura under direct vision. Plasma morphine concentrations measured by specific radioimmunoassay showed that peak concentrations occurred significantly earlier with heroin (4.7 +/- 0.6 min, mean +/- SEM) than with morphine (7.6 +/- 0.9 min) and that peak concentrations were significantly higher after heroin 5-10 min after extradural injection. The fraction of extradural heroin crossing the dura was estimated to be 55% of the fraction of morphine crossing the dura. Postoperative fentanyl requirements using demand analgesia were the same with extradural morphine as with extradural heroin (mean, 6.6 micrograms/hr). Clinically significant slowing of respiratory rate occurred only after extradural heroin (three patients).

Adult↗