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Ronald L Koretz

Publications and source records attributed to Ronald L Koretz.

At least 19 recordsLinked to original sources
PubMed2005

ICU SAFEty.

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Comment↗
PubMed2005

More food please.

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Deglutition↗
PubMed2005

Death, morbidity and economics are the only end points for trials.

In order to determine whether surrogate markers predict clinical outcome, randomized controlled trials (RCT) of nutrition support v. no nutrition support that have reported at least one clinical outcome (mortality, infections, total complications, or duration of hospitalization) and at least one nutritional outcome (energy or protein intake, weight gain, N balance, albumin, prealbumin, transferrin, three anthropometric measures, skin testing, lymphocyte count) were assessed for concordance. If changes in nutritional markers predict clinical outcome, changes in both outcomes should go in the same direction. Concordance is defined as both outcomes changing in the same direction or both outcomes showing no difference. Discordance is defined as one outcome changing and the other not (partial) or both outcomes changing in opposite directions (complete). Ninety-nine RCT were identified, of which most were underpowered to see statistically significant changes, especially in clinical outcomes. Thus, the results were analysed only in relation to the direction of the respective changes in outcomes. Forty-eight comparisons (4 x 12) were made. The rates of concordance were < or =50% in forty-one of forty-eight comparisons; the rate was never >75%. A complete discordance rate of > or =25% was present in forty-three (> or =50% in thirteen) of the forty-eight comparisons. The discordance was usually a result of the nutritional outcome being better than the clinical outcome. Changes in nutritional markers do not predict clinical outcomes. Before adopting any surrogate marker as an end point for a clinical trial, it has to be known that improving it will result in patient benefit.

Biomarkers↗
PubMed2005

Is statistical significance always significant?

One way in which we learn new information is to read the medical literature. Whether or not we do primary research, it is important to be able to read literature in a critical fashion. A seemingly simple concept in reading is to interpret p values. For most of us, if we find a p value that is <.05, we take the conclusion to heart and quote it at every opportunity. If the p value is >.05, we discard the paper and look elsewhere for useful information. Unfortunately, this is too simplistic an approach. The real utility of p values is to consider them within the context of the experiment being performed. Defects in study design can make an interpretation of a p value useless. One has to be wary of type I (seeing a "statistically significant" difference just because of chance) and type II (failing to see a difference that really exists) errors. Examples of the former are publication bias and the performance of multiple analyses; the latter refers to a trial that is too small to demonstrate the difference. Finding significant differences in surrogate or intermediate endpoints may not help us. We need to know if those endpoints reflect the behavior of clinical endpoints. Selectively citing significant differences and disregarding studies that do not find them is inappropriate. Small differences, even if they are statistically significant, may require too much resource expenditure to be clinically useful. This article explores these problems in depth and attempts to put p values in the context of studies.

Clinical Trials as Topic↗
PubMed2004

Complementary and alternative medicine in gastroenterology: the good, the bad, and the ugly.

A large proportion of the American population avails itself of a variety of complementary and alternative medicine (CAM) interventions. Allopathic practitioners often dismiss CAM because of distrust or a belief that there is no sound scientific evidence that has established its utility. However, although not widely appreciated, there are thousands of randomized controlled trials (RCTs) that have addressed the efficacy of CAM. We reviewed the RCTs of herbal and other natural products, acupuncture, and homeopathy as examples of typical CAM modalities, focusing on conditions of interest to gastroenterologists. Peppermint (alone or in combination) has supportive evidence for use in patients with dyspepsia, irritable bowel syndrome, and as an intraluminal spasmolytic agent during barium enemas or endoscopy. Ginger appeared to be effective in relieving nausea and vomiting due to motion sickness or pregnancy. Probiotics were useful in childhood diarrhea or in diarrhea due to antibiotics; one particular formulation (VSL#3) prevented pouchitis. Acupuncture appeared to ameliorate postoperative nausea and vomiting and might be useful elsewhere. There is even a suggestion that homeopathy has efficacy in treatment of gastrointestinal problems or symptoms. The major problem in interpreting these CAM data is the generally low quality of the RCTs, although that quality might not be different compared to RCTs in the general medical literature. Gastroenterologists should become familiar with these techniques; it is likely that their patients already are.

Acupuncture Therapy↗
PubMed2003

Is weight reduction an effective therapy for nonalcoholic fatty liver? A systematic review.

PURPOSE: To assess the evidence supporting the efficacy of weight reduction for patients with nonalcoholic fatty liver. METHODS: Potentially relevant studies were identified by a computerized search of databases and a manual search of abstracts from scientific meetings. Studies were included if they reported histology, serum aminotransferase levels, or radiological imaging of the liver in obese adult patients who had undergone weight reduction. Weight reduction regimens included diet, exercise, antiobesity medications, gastric bypass, gastroplasty, or any combination of these interventions. Studies involving jejunoileal or small bowel bypass surgery were excluded. RESULTS: We identified 517 potentially relevant studies, of which 15 met the inclusion criteria: one randomized controlled trial (in abstract form), two nonrandomized controlled trials, nine case series, one retrospective review, and two case reports. Three studies included more than 50 patients, whereas nine studies had 25 or fewer patients. Twelve studies used behavioral, dietary, or pharmacologic therapy for weight reduction, and three studies used surgical interventions. Although all 15 studies demonstrated overall improvement in the measurements of liver outcome after weight reduction, more than half did not report histologic results. CONCLUSION: Despite general acceptance that weight reduction is an effective therapy for nonalcoholic fatty liver, this systematic review found little data to support or refute this recommendation.

Diet↗