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Biomedical subjects

E Skovlund

Publications and source records attributed to E Skovlund.

6 recordsLinked to original sources
PubMed1991

[Placebo effects and controlled clinical trials].

Placebo effects have been recognized for a long time, but the underlying mechanisms are unknown. The analgesic effect of placebo has been studied, and one hypothesis is that placebo-induced analgesia is mediated by endorphins. The opiate antagonist naloxone has been used in an attempt to prevent this analgesia. Partial antagonism has been shown, but the placebo still has a considerable analgesic effect. This means that release of endorphins cannot be the only explanation of the analgesia. Patients participating in clinical trials to compare an active drug with a placebo are informed that they may receive the latter. This information leads to a reduction of the effect of the active drug. Possibly the participating patients should not be given this information.

Analgesics↗
PubMed1991

Comparison of postpartum pain treatments using a sequential trial design. I. Paracetamol versus placebo.

A new sequential test has been used to compare the effect of paracetamol and placebo on uterine cramping. Paracetamol was significantly superior to placebo at the 5% level. 75 patients were included in the trial, whereas in a fixed sample study 90 patients would have been required to obtain the same significance level and power. The magnitude of the difference in treatment effect was estimated following the sequential test. In addition to the effect on uterine pain, which was the primary variable, the effect on episiotomy pain was also estimated. Paracetamol was also superior to placebo against the episiotomy pain.

Acetaminophen↗
PubMed1991

Comparison of postpartum pain treatments using a sequential trial design: II. Naproxen versus paracetamol.

The efficacy of naproxen and paracetamol in relieving uterine cramps has been compared in a sequential trial. The treatments did not differ significantly in a two-sided test in 56 patients. A corresponding fixed sample test would have required 140 patients to obtain the same significance level and power. In addition to uterine pain, the effect on episiotomy pain was also estimated at the termination of the trial. Again, there seemed to be no difference between naproxen and paracetamol.

Acetaminophen↗
PubMed1991

Sequential or fixed sample trial design? A case study by stochastic simulation.

The properties of Wilcoxon's rank sum test for fixed sample size and a Wilcoxon-type two-sample sequential test have been illustrated and compared by means of stochastic simulation. Data from a real fixed sample trial have been used, both for resampling from the original data, and for construction of an idealized theoretical distribution. The sequential and the fixed sample test obtain equal power, but the sequential test mostly includes considerably fewer patients to reach a conclusion, i.e. the mean and median number of patients included are both much lower than the fixed sample size. Under the hypotheses only a small fraction of the simulation runs exceed the fixed sample size. These findings exemplify results obtained in theoretical analyses and simulation studies covering a wide range of distributions. In our opinion sequential tests have obvious advantages and are in many cases better alternatives than fixed sample tests in clinical trials.

Clinical Trials as Topic↗