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Biomedical subjects

A Hróbjartsson

Publications and source records attributed to A Hróbjartsson.

9 recordsLinked to original sources
PubMed2005

Somatostatin analogues for acute bleeding oesophageal varices.

BACKGROUND: Somatostatin and its derivatives are often used for emergency treatment of bleeding oesophageal varices in patients with cirrhosis of the liver. OBJECTIVES: To study whether somatostatin or analogues improve survival or reduce the need for blood transfusions in patients with bleeding oesophageal varices. SEARCH STRATEGY: MEDLINE and The Cochrane Library were searched; last search in Febr 2004. Reference lists of articles, contacted authors. SELECTION CRITERIA: All randomised trials comparing somatostatin or analogues with placebo or no treatment in patients suspected of acute or recent bleeding from oesophageal varices. DATA COLLECTION AND ANALYSIS: The effect variables extracted were: mortality, blood transfusions, use of balloon tamponade, initial haemostasis and rebleeding. Intention-to-treat analyses including all randomised patients were conducted; a random effects analysis was preferred if there was significant heterogeneity between the trials (P < 0.10). The trials were divided in two quality groups; the better trials had concealed allocation of patients and were double-blind. MAIN RESULTS: We included 20 trials (2518 patients). The drugs did not reduce mortality significantly (relative risk 0.96, 95% confidence interval 0.74 to 1.24, for the high-quality trials, and 0.79 for low-quality trials). Units of blood transfused were 0.7 (0.3 to 1.2) less with drugs in the high-quality trials and 1.5 (0.9 to 2.0) less in the low-quality trials. Number of patients failing initial haemostasis was reduced, relative risk 0.67 (0.53 to 0.86). Number of patients with rebleeding was not significantly reduced for the high-quality trials, relative risk 0.82 (0.45 to 1.49) while it was substantially reduced in the low-quality trials, relative risk 0.35 (0.18 to 0.67). Use of balloon tamponade was rarely reported. AUTHORS' CONCLUSIONS: The effect corresponded to one half unit of blood saved per patient. It is doubtful whether this effect is worthwhile. The findings do not suggest a need for further placebo-controlled studies of the type reviewed here. A large placebo controlled trial enrolling thousands of patients is needed if one wishes to rule out the possibility that a worthwhile effect on mortality may have been overlooked.

Acute Disease↗
PubMed2004

Placebo interventions for all clinical conditions.

BACKGROUND: Placebo interventions are often claimed to improve patient-reported and observer-reported outcomes, but this belief is not based on evidence from randomised trials that compare placebo with no treatment. OBJECTIVES: To assess the effect of placebo interventions. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 4, 2002), MEDLINE (1966 to 2002), EMBASE (1980 to 2002), Biological Abstracts (1986 to 2002), and PsycLIT (1887 to 2002). We contacted experts on placebo research, and read references in the included trials. SELECTION CRITERIA: We included randomised placebo trials with a no-treatment control group investigating any health problem. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial quality and extracted data. We contacted study authors for additional information. MAIN RESULTS: Outcome data were available in 156 out of 182 included trials, investigating 46 clinical conditions. We found no statistically significant pooled effect of placebo in 38 studies with binary outcomes (4284 patients), relative risk 0.95 (95% confidence interval (CI) 0.89 to 1.01). The pooled relative risk for patient-reported outcomes was 0.95 (95% CI 0.88 to 1.03) and for observer-reported outcomes 0.91 (95% CI 0.81 to 1.03). There was heterogeneity (P=0.01) but the funnel plot was symmetrical. There was no statistically significant effect of placebo interventions in the four clinical conditions investigated in three trials or more: pain, nausea, smoking, and depression, but confidence intervals were wide. We found an overall effect of placebo treatments in 118 trials with continuous outcomes (7453 patients), standardised mean difference (SMD) -0.24 (95% CI -0.31 to -0.17). The SMD for patient-reported outcomes was -0.30 (95% CI -0.38 to -0.21), whereas no statistically significant effect was found for observer-reported outcomes, SMD -0.10 (95% CI -0.20 to -0.01). There was heterogeneity (P<0.001) and large variability in funnel plot results even for big trials. There was an apparent effect of placebo interventions on pain (SMD -0.25 (95% CI -0.35 to-0.16)), and phobia (SMD -0.63 (95% CI -1.17 to -0.08)); but also a substantial risk of bias. There was no statistically significant effect of placebo interventions in eight other clinical conditions investigated in three trials or more: nausea, smoking, depression, overweight, asthma, hypertension, insomnia and anxiety, but confidence intervals were wide. REVIEWERS' CONCLUSIONS: There was no evidence that placebo interventions in general have clinically important effects. A possible small effect on continuous patient-reported outcomes, especially pain, could not be clearly distinguished from bias.

Humans↗
PubMed2004

Is the placebo powerless? Update of a systematic review with 52 new randomized trials comparing placebo with no treatment.

BACKGROUND: It is widely believed that placebo interventions induce powerful effects. We could not confirm this in a systematic review of 114 randomized trials that compared placebo-treated with untreated patients. AIM: To study whether a new sample of trials would reproduce our earlier findings, and to update the review. METHODS: Systematic review of trials that were published since our last search (or not previously identified), and of all available trials. RESULTS: Data was available in 42 out of 52 new trials (3212 patients). The results were similar to our previous findings. The updated review summarizes data from 156 trials (11 737 patients). We found no statistically significant pooled effect in 38 trials with binary outcomes, relative risk 0.95 (95% confidence interval 0.89-1.01). The effect on continuous outcomes decreased with increasing sample size, and there was considerable variation in effect also between large trials; the effect estimates should therefore be interpreted cautiously. If this bias is disregarded, the pooled standardized mean difference in 118 trials with continuous outcomes was -0.24 (-0.31 to -0.17). For trials with patient-reported outcomes the effect was -0.30 (-0.38 to -0.21), but only -0.10 (-0.20 to 0.01) for trials with observer-reported outcomes. Of 10 clinical conditions investigated in three trials or more, placebo had a statistically significant pooled effect only on pain or phobia on continuous scales. CONCLUSION: We found no evidence of a generally large effect of placebo interventions. A possible small effect on patient-reported continuous outcomes, especially pain, could not be clearly distinguished from bias.

Humans↗
PubMed2003

Placebo treatment versus no treatment.

BACKGROUND: Placebo interventions are often believed to improve patient reported and observer reported outcomes, but this belief is not based on evidence from randomised trials that compare placebo with no treatment. OBJECTIVES: To assess the effect of placebo interventions. SEARCH STRATEGY: We searched the Cochrane Controlled Trials Register (The Cochrane Library, issue 3, 1998), MEDLINE (Jan 1966 to Dec 1998), EMBASE (Jan 1980 to Dec 1998), Biological Abstracts (Jan 1986 to Dec 1998), PsycLIT (Jan 1887 to Dec 1998). Experts on placebo research were contacted and references in the included trials were read. SELECTION CRITERIA: Randomised placebo trials with a no-treatment control group investigating any health problem were included. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial quality and extracted data. Study authors were contacted for additional information. MAIN RESULTS: Outcome data were available in 114 out of 130 included trials, investigating 40 clinical conditions. Outcomes were binary in 32 trials (3795 patients) and continuous in 82 (4730 patients). We found no statistically significant pooled effect of placebo in studies with binary outcomes, relative risk 0.95 (95 per cent confidence interval 0.88 to 1.02). The pooled relative risk for subjective (patient reported) outcomes was 0.95 (0.86 to 1.05) and for objective (observer reported) outcomes 0.91 (0.80 to 1.04). There was statistically significant heterogeneity (P < 0.03), but no evidence of sample size bias (P = 0.56). We found an overall positive effect of placebo treatments in trials with continuous outcomes, standardised mean difference -0.28 (95 per cent confidence interval -0.38 to -0.19). The standardised mean difference for subjective outcomes was -0.36 (-0.47 to -0.25), whereas no statistically significant effect was found for objective outcomes, standardised mean difference -0.12 (-0.27 to 0.03). There was statistically significant heterogeneity (P < 0.001), and evidence of sample size bias (P = 0.05). There was no statistically significant effect of placebo interventions in eight out of nine clinical conditions investigated in three trials or more (nausea, relapse in prevention of smoking and depression, overweight, asthma, hypertension, insomnia and anxiety), but confidence intervals were wide. There was a modest apparent analgesic effect of placebo interventions, standardised mean difference -0.27 (-0.40 to -0.15), but also a substantial risk of bias. REVIEWER'S CONCLUSIONS: There was no evidence that placebo interventions in general have clinically important effects. A possible moderate effect on subjective continuous outcomes, especially pain, could not be clearly distinguished from bias.

Humans↗
PubMed2002

Low agreement among 24 doctors using the Neer-classification; only moderate agreement on displacement, even between specialists.

Twenty-four orthopaedic surgeons classified 42 pairs of radiographs according to the Neer system for proximal humeral fractures. Mean kappa value for inter-observer agreement was 0.27 (95% CI 0.26-0.28) with no clinically significant difference between orthopaedic residents ( n=9), fellows ( n=6) and specialists ( n=9). Mean kappa for agreement of displacement versus non-displacement was 0.41 (95% CI 0.39-0.43) overall, and 0.50 (95% CI 0.45-0.56) within the specialist group. The agreement found in our study is unsatisfactory from a clinical perspective.

Confidence Intervals↗
PubMed2001

Is the placebo powerless? An analysis of clinical trials comparing placebo with no treatment.

BACKGROUND: Placebo treatments have been reported to help patients with many diseases, but the quality of the evidence supporting this finding has not been rigorously evaluated. METHODS: We conducted a systematic review of clinical trials in which patients were randomly assigned to either placebo or no treatment. A placebo could be pharmacologic (e.g., a tablet), physical (e.g., a manipulation), or psychological (e.g., a conversation). RESULTS: We identified 130 trials that met our inclusion criteria. After the exclusion of 16 trials without relevant data on outcomes, there were 32 with binary outcomes (involving 3795 patients, with a median of 51 patients per trial) and 82 with continuous outcomes (involving 4730 patients, with a median of 27 patients per trial). As compared with no treatment, placebo had no significant effect on binary outcomes (pooled relative risk of an unwanted outcome with placebo, 0.95; 95 percent confidence interval, 0.88 to 1.02), regardless of whether these outcomes were subjective or objective. For the trials with continuous outcomes, placebo had a beneficial effect (pooled standardized mean difference in the value for an unwanted outcome between the placebo and untreated groups, -0.28; 95 percent confidence interval, -0.38 to -0.19), but the effect decreased with increasing sample size, indicating a possible bias related to the effects of small trials. The pooled standardized mean difference was significant for the trials with subjective outcomes (-0.36; 95 percent confidence interval, -0.47 to -0.25) but not for those with objective outcomes. In 27 trials involving the treatment of pain, placebo had a beneficial effect (-0.27; 95 percent confidence interval, -0.40 to -0.15). This corresponded to a reduction in the intensity of pain of 6.5 mm on a 100-mm visual-analogue scale. CONCLUSIONS: We found little evidence in general that placebos had powerful clinical effects. Although placebos had no significant effects on objective or binary outcomes, they had possible small benefits in studies with continuous subjective outcomes and for the treatment of pain. Outside the setting of clinical trials, there is no justification for the use of placebos.

Anxiety↗
PubMed1996

The uncontrollable placebo effect.

OBJECTIVE: To analyse the role of the control group in the methodology of clinical placebo effect evaluating trials. SETTING: Department of Medical Philosophy and Clinical Theory, University of Copenhagen. METHODS: A theoretical methodological analysis. RESULTS: At least with present trial designs, it is impossible, with certainty, to exclude a potential placebo effect from the so-called control group. The placebo effect, in other words, is uncontrollable. CONCLUSION: I suggest that the notions of control group and placebo treatment group are replaced by the notions of "placebo effect maximising group" and "placebo effect minimising group", thus stressing the fact that what such trials measure is a relative effect, and an underestimation of the absolute placebo effect. The illusion of absolute placebo effect evaluation must be acknowledged when articles referring to empirical trials on the placebo effect are interpreted.

Controlled Clinical Trials as Topic↗