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Biomedical subjects

G ter Riet

Publications and source records attributed to G ter Riet.

18 recordsLinked to original sources
PubMed1999

The Zelen design may be the best choice for a heroin-provision experiment.

Recently, the Dutch Parliament agreed upon the conduct of a randomized clinical trial on the effects on heroin provision on general health and psychosocial and criminal behavior in long-term addicts. Previous studies failed to establish the effects beyond reasonable doubt. The main reasons why previous trials failed are massive dropout or noncompliance in the control group. Designing a new heroin-provision trial, we concluded that the Zelen design provides the best guarantee for obtaining valid study results. Compared with the traditional design, the Zelen design probably reduces noncompliance and dropout considerably, thus increasing validity. Depending on the study population, the Zelen design may reduce study precision. However, in a trial aimed at badly integrated addicts, the Zelen design can be conducted without loss of precision because baseline measurements will only weakly correlate with effect measurements. The arguments favoring the Zelen design may be generalized to trials in which the experimental treatment is highly attractive to the study participants. However, the use of the Zelen design precludes blinding of participants who receive the experimental treatment. We argue that the conduct of studies that predictably tend to produce invalid results is ethically dubious. The ethical problem of studying participants without their consent can be solved by a slight modification of the Zelen design in which the sampling of a control group is postponed. Both the traditional and the Zelen design can imply ethical problems. Both designs can be ethically justifiable and should not be rejected on a priori grounds.

Analgesics, Opioid↗
PubMed1999

A successful short-bowel syndrome model in neonatal piglets.

BACKGROUND: With the higher survival rate of premature neonates as a result of improved neonatal intensive care, the incidence of necrotizing enterocolitis, and thus the incidence of short-bowel syndrome, is increasing. An appropriate animal model resembling the (premature) neonate with short-bowel syndrome suitable for clinically relevant neonatal bowel adaptation and intervention studies, is not available at present. The purpose of this study was the development of a short-bowel syndrome model that mimics the clinical state of the affected neonatal patient. METHODS: Sixteen 7-day-old piglets received either a small bowel transection (group A) or a 75% resection (group B). The piglets were fed 125 kcal/kg body weight per day, including additional electrolytes. The animals were weighed daily and were killed 28 days after surgery. Bowel samples were obtained at both time points. RESULTS: Mortality rates in groups A and B were 0% and 8%, respectively. Body weight gain was significantly higher in group A than in group B (156% vs. 93%; P = 0.01). Jejunal villus length was higher in group B than in group A (74% vs. -2%; P = 0.006), and crypt depth was higher in group B in both jejunum (201% vs. 67%; P = 0.001) and ileum, (197% vs. 20%; P = 0.001), than in group A. CONCLUSIONS: In 7-day-old piglets 75% small bowel resection leads to a clinical short-bowel syndrome, demonstrated by reduced weight gain and typical changes in bowel adaptation parameters. The excellent survival of the animals provides a possibility for the study of bowel adaptation in a neonatal model as well as in intervention studies.

Adaptation, Physiological↗
PubMed1997

Pregnancy rate following normal versus abnormal hysterosalpingography findings: a meta-analysis.

A computerized Medline search was conducted, to assess the prognostic value of hysterosalpingography (HSG) and the probability of pregnancy after normal versus abnormal HSG findings. A total of 13 studies turned out to be eligible, reporting on 3,277 women. 15% of women with an abnormal HSG and 32% of women with a normal HSG achieved pregnancy. Sensitivities and specificities of the studies were heterogeneous. The pooled odds ratio was 3 (95% CI: 2.3-3.4). Its ROC Curve shows that, at the operating point yielding the lowest number of misclassifications, a sensitivity of 63% and a specificity of 62% is achieved. Seven studies reported unilateral and bilateral obstruction. Odds ratios were 2(95% CI: 1.5-2.6) and 19(95% CI: 7.5-46.5) respectively. So, overall, HSG has a low prognostic value, the outcome of HSG adds little to predicting the occurrence of pregnancy. However, when HSG shows bilateral obstruction, the chance of getting pregnant is only minimal.

Fallopian Tube Diseases↗
PubMed1996

A randomized clinical trial of ultrasound in the treatment of pressure ulcers.

BACKGROUND AND PURPOSE: The purpose of this study was to assess the effects of ultrasound (US) therapy in the treatment of pressure ulcers as an adjunct to standardized treatment. SUBJECTS: Eighty-eight patients from 11 nursing homes and one hospital participated. Subjects were randomly assigned to either a US group (n = 45) or a sham US group (n = 43). METHODS: This was a multicenter placebo-controlled randomized trial. Wound survival, healing rates of wound surfaces, and changes on a clinical rating scale were measured over 12 weeks. RESULTS: Comparison of the 12-week cumulative incidences of wound closure showed that 40% (18/45) of ulcers in the US group and 44% (19/43) of ulcers in the sham US group were closed. An analysis in which between-group baseline differences and the days of wound closures were accounted for showed that the wound closure probability per unit of time (ie, closure rate) was almost equal in the two treatment groups (Cox proportional-hazards ratio of 1.08). Mean absolute healing rates were 0.18 and 0.31 cm2/wk in the US and sham US groups, respectively. Relative healing rates and healing speeds were similar in the two treatment groups. A panel scored slides of the ulcers with a report mark between 1 (bad) and 10 (excellent). The improvement was 0.71 and 0.46 points per week in the US and sham US groups, respectively. CONCLUSION AND DISCUSSION: These data do not support the idea that US speeds up the healing of pressure ulcers.

Aged↗
PubMed1995

Randomized clinical trial of ascorbic acid in the treatment of pressure ulcers.

The objective of this study was to assess the effects of ascorbic acid supplementation, 500 mg twice daily in the treatment of pressure ulcers as an adjunct to standardized treatment. The design consisted of a multicenter blinded randomized trial. The control group received 10 mg of ascorbic acid twice daily. Patients from 11 nursing homes and 1 hospital participated. Main outcome measures included wound survival, healing rates of wound surfaces, and clinimetric changes over 12 weeks. Eighty-eight patients were randomized. Intention-to-treat analysis showed that the wound closure probability per unit time (i.e., the closure rate) was not higher in the intervention group than in the control group (Cox hazard ratio of 0.78 [90% precision interval, 0.44-1.39]). Mean absolute healing rates were 0.21 and 0.27 cm2/week in the intervention and control group, respectively (PI of the adjusted difference: -0.17 to 0.13). Relative healing rates and healing velocities did not show favorable results of ascorbic acid supplementation, either. A panel scored slides of the ulcers with a report mark between 1 (bad) and 10 (excellent). The improvement was 0.45 and 0.72 points per week in the intervention and control group, respectively (PI of the adjusted difference: -0.50 to 0.20). With another clinimetric index we could not show any differences, either. These data do not support the idea that ascorbic acid supplementation (500 vs. 10 mg twice daily) speeds up the healing of pressure ulcers.

Ascorbic Acid↗
PubMed1991

Trials of homeopathy.

Explore the source record for details and available documents.

Clinical Trials as Topic↗
PubMed1991

Clinical trials of homoeopathy.

OBJECTIVE: To establish whether there is evidence of the efficacy of homoeopathy from controlled trials in humans. DESIGN: Criteria based meta-analysis. Assessment of the methodological quality of 107 controlled trials in 96 published reports found after an extensive search. Trials were scored using a list of predefined criteria of good methodology, and the outcome of the trials was interpreted in relation to their quality. SETTING: Controlled trials published world wide. MAIN OUTCOME MEASURES: Results of the trials with the best methodological quality. Trials of classical homoeopathy and several modern varieties were considered separately. RESULTS: In 14 trials some form of classical homoeopathy was tested and in 58 trials the same single homoeopathic treatment was given to patients with comparable conventional diagnosis. Combinations of several homoeopathic treatments were tested in 26 trials; isopathy was tested in nine trials. Most trials seemed to be of very low quality, but there were many exceptions. The results showed a positive trend regardless of the quality of the trial or the variety of homeopathy used. Overall, of the 105 trials with interpretable results, 81 trials indicated positive results whereas in 24 trials no positive effects of homoeopathy were found. The results of the review may be complicated by publication bias, especially in such a controversial subject as homoeopathy. CONCLUSIONS: At the moment the evidence of clinical trials is positive but not sufficient to draw definitive conclusions because most trials are of low methodological quality and because of the unknown role of publication bias. This indicates that there is a legitimate case for further evaluation of homoeopathy, but only by means of well performed trials.

Clinical Trials as Topic↗
PubMed1991

Acupuncture and asthma: a review of controlled trials.

BACKGROUND: Published controlled trials of acupuncture in asthma have often contained a small number of subjects and the results are contradictory. Controlled trials have been reviewed to determine whether clearer conclusions could be obtained by assessing as many studies as possible according to methodological criteria. METHODS: A literature search produced 13 trials on the efficacy of acupuncture in the treatment of patients with asthma. These studies were reviewed on the basis of 18 predefined methodological criteria. A maximum of 100 points for study design could be earned in three main categories: (a) adequate study population, (b) adequate intervention, and (c) adequate measurement of effects. RESULTS: The quality of even the eight better studies (more than 50% of the maximum score) proved to be mediocre. No study earned more than 72% of the maximum score. The results from the better studies are highly contradictory. CONCLUSIONS: Claims that acupuncture is effective in the treatment of asthma are not based on the results of well performed clinical trials.

Acupuncture Therapy↗
PubMed1990

Acupuncture and chronic pain: a criteria-based meta-analysis.

A literature search revealed 51 controlled clinical studies on the effectiveness of acupuncture in chronic pain. These studies were reviewed using a list of 18 predefined methodological criteria. A maximum of 100 points for study design could be earned in four main categories: (a) comparability of prognosis, (b) adequate intervention, (c) adequate effect measurement and (d) data presentation. The quality of even the better studies proved to be mediocre. No study earned more than 62% of the maximum score. The results from the better studies (greater than or equal to 50% of the maximum score) are highly contradictory. The efficacy of acupuncture in the treatment of chronic pain remains doubtful.

Acupuncture Analgesia↗
PubMed1989

Vitamin E and cardiovascular disease.

Randomized clinical trials of the effects of Vitamin E on complaints of intermittent claudication and angina pectoris are reviewed, and their methodological shortcomings are considered. Mechanisms by which Vitamin E might act in cardiovascular disease are discussed. The evidence about the possible pharmacological actions of Vitamin E supports the need for randomized clinical trials. It is concluded that Vitamin E may have a positive effect, especially in intermittent claudication.

Angina Pectoris↗
PubMed1989

Garlic, onions and cardiovascular risk factors. A review of the evidence from human experiments with emphasis on commercially available preparations.

1. Claims for beneficial effects on cholesterol levels, fibrinolytic activity, and platelet aggregation are attributed both to fresh garlic and onions (or their extracts) and to commercially available preparations. 2. Regarding fresh garlic, the claims have been confirmed, but so far only at very high dosages. 3. For onions and commercially available supplements contradictory results have been reported. 4. All published trials showed severe methodological shortcomings. Some trials were not randomized and/or not blinded whilst this was possible, and in only one of every three studies more than 25 patients participated in each treatment group. In no trial was prognostic comparability of the treatment and the control groups ascertained. At the moment there is inadequate scientific justification for garlic supplementation.

Allium↗