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Results for “Meta-analyses”

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PubMedDate not supplied

Critical reading of the meta-analysis of clinical trials.

In this paper we shall present the general principles of meta-analysis and will then discuss the various factors needed to evaluate a meta-analysis: description of the problem; definition of the outcome(s) (primary and secondary); methods for identifying and selecting trials for inclusion; statistical methods used; and the presentation and discussion of the results. We shall then examine other problems such as the detection of bias, the validity of the information provided by the meta-analysis, the problem of heterogeneity, the sensitivity and robustness of the meta-analysis, quality criteria for a meta-analysis, and how to locate published meta-analyses. Finally we present a decision algorithm which should help answer the question: should and can the results from the meta-analysis be integrated into clinical practice?

Bias↗

PubMedDate not supplied

A meta-analytical approach examining the potential relationship between talc exposure and ovarian cancer.

The concern that use of talc or talc-containing substances in the perineal region of women may subject them to an increased risk for ovarian cancer has become an important issue in the study of ovarian cancer. The purpose of this paper is to examine whether this concern, heightened by several epidemiological studies purporting to show an increased risk, is valid. Epidemiological studies examining the possibility of this relationship are reviewed, and meta-analyses of their results are performed. The conclusion reached herein is that the evidence regarding the risk of ovarian cancer associated with talc exposure is equivocal, and further examination of the relationship is required before a sound conclusion can be made.

Adult↗

PubMedDate not supplied

[Effectiveness of psychotherapy in asthma: meta-analysis].

Various works have been done to find the efficiency of different psychotherapies of asthma. The results are sceptical and sometimes contradictory; this contradiction probably is due to the multiple methods or also to the various variables linked to the illness. The results of our meta-analyses on 74 hypotheses chosen by specific criteria show the efficiencies of all these psychotherapies in asthma; however, these results are largely dependent on the 8 variables taken into account.

Asthma↗

PubMed1995

Role of Helicobacter pylori in gastrointestinal disease: implications for primary care of a revolution in management of dyspepsia.

The majority of patients with dyspepsia are managed in general practice. However, most of the literature on Helicobacter pylori and its association with gastrointestinal disease has originated from secondary care. This review summarizes the role of H pylori in dyspepsia from the perspective of primary care and suggests a new strategy for the management of dyspeptic patients in this setting. Recent meta-analyses and consensus statements have supported the use of eradication therapy as first-line treatment of peptic ulceration. Studies from primary care have supported the use of eradication therapy in patients who have H pylori related peptic ulcer disease and require long-term H2-antagonist medication, on both clinical benefit and cost-effectiveness grounds. Of the many regimens proposed for the eradication of H pylori, the best evidence supports a triple combination of bismuth, metronidazole and tetracycline. Regimens using proton pump inhibitors may be more acceptable to patients but lack good evidence from trials. Use of a positive serum enzyme-linked immunoabsorbent assay for H pylori antibodies as a criterion for endoscopic investigation has been shown to result in a 23% reduction in endoscopic workload. Further research should answer questions of importance to general practitioners, such as the role of eradication therapy in patients with nonulcer dyspepsia and the effectiveness of eradication of H pylori in the prevention of gastric cancer.

Dyspepsia↗

PubMed1994

Cardiovascular structural changes and calcium antagonist therapy in patients with hypertension.

Regression of cardiovascular structural changes is a main goal of antihypertensive treatment. Two recent meta-analyses of relatively small noncomparative studies have suggested that angiotensin-converting enzyme (ACE) inhibitors may be more effective than other classes of drugs in inducing regression of left ventricular hypertrophy (LVH). The effect of different antihypertensive drugs on arteriolar structural changes has not yet been properly investigated. The aim of this study was to evaluate the effect of 6 months of treatment with amlodipine (5-10 mg o.d.) or enalapril (10-20 mg o.d.) on blood pressure (BP) (ambulatory monitoring), heart rate (HR), LV mass and function (M-mode echo, two-dimensionally guided), forearm minimal vascular resistance (min VR = BP/max blood flow-venous occlusion plethysmography, taken as an index of vascular structural changes) in 24 hypertensive patients in a comparative single-blind, randomized study, with blind reading of echocardiograms and plethysmographic tracings. After 6 months of treatment with amlodipine 5-10 mg o.d., significant reductions in LV mass index (p = 0.004) and forearm min VR (p = 0.02) were observed. Before and during treatment, LV systolic function, both at rest and during stress (handgrip test), evaluated by fractional shortening as related to end-systolic stress, was in every case within 95% confidence limits calculated in normal subjects. Similar results were observed with enalapril. No significant differences were observed for Doppler indices of diastolic filling after 6 months of treatment with either drug. These results indicate that a significant regression of structural changes in the heart and in the small resistance vessels can be observed after long-term treatment with amlodipine in essential hypertensive patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

The management of menopausal symptoms in women with breast cancer.

The symptomatic postmenopausal woman with breast cancer presents the clinician with a difficult task with respect to hormone replacement therapy (HRT). All of the published meta-analyses have been consistent in showing that there is a slightly increased risk of developing breast cancer in those patients using postmenopausal estrogens for greater than 10 years. However, there have been no published placebo-controlled clinical trials on the effects of HRT in women with a history of breast cancer. Quality of life must be balanced against the theoretical risk of tumor promotion. Assessment of osteoporotic and cardiac risk factors (i.e., smoking, hypertension, family history, hyperlipidemia) should influence the decision. Valid alternatives to estrogen replacement include low-dose progesterones such as Bellergal or vitamin E for hot flashes, and biphosphonates, calcium, anabolic steroids, and calcitonin for osteoporosis.

Breast Neoplasms↗

PubMed1995

Why should rheumatologists collect patient self-report questionnaires in routine rheumatologic care?

In this article, a rationale for routine use of self-report questionnaires in rheumatology clinical care is presented. Studies performed according to structured clinical research methodologies, including population-based studies, inception cohort studies, randomized controlled clinical trials, and meta-analyses of these trials, have significant limitations in describing accurately the long-term natural history and results of treatment of rheumatoid arthritis; the most accurate data have been derived from clinical observations of consecutive, nonselected patients in routine clinical settings. Self-report questionnaires provide accurate and representative data concerning clinical status and traditional laboratory and variables in large numbers of patients can be developed using microcomputer hardware and software available only over the last decade. Further collection of self-report data in rheumatology clinical care should result in more informative descriptions of the long-term natural history and results of therapy in rheumatoid arthritis.

Humans↗

PubMed1995

[Hyperlipoproteinemia as a risk factor for ischemic heart disease. Epidemiologic and interventional studies].

The author reviews the main epidemiological studies which identified a number of risk factors of ischaemic heart disease and became the basis for widely accepted ranges of lipids where dietary or medicamentous intervention should be used. She emphasizes in particular the evaluation of the total risk not only from the aspect of various lipid indicators but also non-lipid risk factors. The author reviews the main hypolipidaemic intervention studies and their meta-analyses. She emphasizes the importance of hitherto not widely accepted hypolipidaemic treatment in secondary prevention of ischaemic heart disease, which reduced not only cardiovascular but also total mortality. The author gives also an account of coronarography-based intervention studies which provide evidence that intensive hypolipidaemic treatment leads not only to arrested progression but may induce regression of atherosclerotic vascular changes.

Coronary Artery Disease↗

PubMed1995

Somatostatin and octreotide in the management of acute variceal hemorrhage.

In recent years, somatostatin and its long-acting analogue octreotide have been used as the initial treatment in acute variceal hemorrhage, with conflicting results. The aim of this study was to meta-analyse all the randomised controlled trials published in English, in which somotostatin or octreotide was compared with other vasoactive drugs, balloon tamponade and endoscopic sclerotherapy in variceal hemorrhage. Concerning the control of bleeding, somatostatin or octreotide therapy was shown to be significantly better than the other vasoactive drugs (p < 0.0012, x2 = 10.55). In contrast, the effectiveness of both agents appeared to be similar to that of balloon tamponade and sclerotherapy in arresting acute variceal hemorrhage during the infusion period. Regarding the complication rate, it appears that treatment with somatostatin or octreotide is followed by a significantly lower complication rate as compared with the other vasoactive drugs (p < 0.0001, x2 = 16.47) as well as than endoscopic sclerotherapy (p, 0.0002, x2 = 14.16). In conclusion, the results of this study suggest that in acute variceal hemorrhage, somatostatin or octreotide is better than any other combination of vasoactive drugs. As regards comparison with sclerotherapy or balloon tamponade, further evidence of benefit is needed before a recommendation can be made for the use of instead of these two kind of treatments of the former procedures.

Acute Disease↗

PubMed1995

[Nutrition and coronary heart disease: how important is diet?].

Three saturated fatty acids (C 12:0, C 14:0, C 16:0) raise LDL cholesterol but also HDL cholesterol levels. Replacement of these fatty acids by monounsaturated or omega-6 polyunsaturated fatty acids will lower LDL cholesterol as well as HDL cholesterol levels. Fat modified diets therefore may not improve the ratio of LDL to HDL cholesterol. Linoleic acid enhances sterol excretion but also increases cholesterol synthesis so that total body cholesterol is not diminished. Moreover various potentially adverse effects have been reported for n-6 polyunsaturated fatty acids. Recent cross-cultural ecologic studies as well as all major within-population cohort studies have not been able to find an association between cholesterol raising saturated fatty acids of animal fat and risk of Coronary Heart Disease (CDH). On the other hand several cohort and case control studies have shown an increase in CHD risk with increasing consumption of partly hydrogenated vegetable margarines. Meta-analyses of controlled intervention studies reveal that cholesterol lowering diets have failed to lower risk of CHD or total mortality. Yet controlled studies implementing a high level of antioxidants in the diet or increasing the n-3 unsaturated fatty acid content have been able to lower CHD and total mortality. It is time to discuss whether the concept of dietary intervention with the "classic" cholesterol lowering diet is still justified.

Antioxidants↗

PubMed1995

Effect of maternal cigarette smoking on pregnancy complications and sudden infant death syndrome.

BACKGROUND: The purpose of this study was to estimate the annual morbidity and mortality among fetuses and infants that can be attributed to the use of tobacco products by pregnant women. METHODS: Published research reports identified by literature review were combined in a series of meta-analyses to compute pooled risk ratios, which, in turn, were used to determine the population attributable risk. RESULTS: Each year, use of tobacco products is responsible for an estimated 19,000 to 141,000 tobacco-induced abortions, 32,000 to 61,000 infants born with low birthweight, and 14,000 to 26,000 infants who require admission to neonatal intensive care units. Tobacco use is also annually responsible for an estimated 1900 to 4800 infant deaths resulting from perinatal disorders, and 1200 to 2200 deaths from sudden infant death syndrome (SIDS). CONCLUSIONS: Tobacco use is an important preventable cause of abortions, low birthweight, and deaths from perinatal disorders and SIDS. All pregnant women should be advised that smoking places their unborn children in danger. The low success rate of smoking cessation among pregnant women suggests that efforts to reduce the complications of pregnancy attributable to tobacco use by pregnant women should focus on preventing nicotine addiction among teenaged girls.

Abortion, Spontaneous↗

PubMed1995

[Proving the effectiveness of complementary therapy. Analysis of the literature exemplified by acupuncture].

At present, acupuncture may be considered one of the most popular forms of complementary medicine worldwide. However, in relation to the number of reviews on the subject, comparatively few controlled clinical trials have been reported so far. An analysis of all the controlled clinical trials listed in MEDLINE between 1987 and March 1994 (n = 39) that met certain basic requirements revealed that they addressed a wide variety of diseases and/or symptoms with no major focus (apart from the symptom of pain, which of course is highly complex in nature). In agreement with the findings of other meta-analyses, most of the more recent papers have been found to be still of indifferent quality. Besides the inherent problem that the term acupuncture subsumes within itself a substantial number of different techniques (and even philosophies), an obvious methodological deficit can be observed. Many groups seem to attach too little importance to choosing an appropriate control model, although seminal papers addressing this problem were already published in the early eighties. Similar remarks apply to inadequacies in study design, which should be at least single-blind. In summary, these findings may well help to explain why the effectiveness of acupuncture has still not been definitively demonstrated.

Acupuncture Therapy↗

PubMed1995

[Breast carcinoma--revision of after-care recommendations. 1: Results of many large studies from the literature are in agreement].

In the past, recommendations for the follow-up of women who had undergone primary treatment for local or locoregional breast cancer, were mostly concerned with "programmed" protocols in which the frequency of the follow-up appointments, and the examinations to be performed on the respective occasions (e.g. bone scintigraphy, chest X-ray, abdominal ultrasound, mammography and laboratory investigations) were rigidly fixed. Numerous new facts reported in the literature (including prospective randomized studies and meta-analyses) now appear to show that this formalized approach to follow-up brings the patient no advantage in terms of approved chances of being cured, longer survival or better quality of life. For this reason, for breast cancer follow-up, a strategy is proposed that is based on meticulous history-taking and clinical examination, and which also emphasizes psychosocial rehabilitation aspects. Examinations using technical equipment are carried out only when justified by clinical suspicion of recurrent disease.

Aftercare↗

PubMed1994

Iterative generalized least squares for meta-analysis of survival data at multiple times.

A method is presented for joint analysis of survival proportions reported at multiple times in published studies to be combined in a meta-analysis. Generalized least squares is used to fit linear models including between-trial and within-trial covariates, using current fitted values iteratively to derive correlations between times within studies. Multi-arm studies and nonrandomized historical controls can be included with no special handling. The method is illustrated with data from two previously published meta-analyses. In one, an early treatment difference is detected that was not apparent in the original analysis.

Antineoplastic Agents↗

PubMed1995

Benefits and costs of screening and treatment for early breast cancer. Development of a basic benefit package.

OBJECTIVE: To develop a basic benefit package for detection and treatment of early breast cancer by evaluating the effectiveness and costs for screening mammography, primary surgery, adjuvant therapy, and follow-up care. DATA SOURCES: Published articles were retrieved through MEDLINE; additional articles were obtained through searches of their bibliographies. Cancer statistics were taken from Surveillance, Epidemiology, and End Results (SEER) Program data, population statistics were taken from US Census data, and charges from 1993 Southern California Medicare fees were used to represent costs. STUDY SELECTION: Studies were selected on the basis of their design. Preference, in decreasing order, was given to meta-analyses of randomized trials, individual randomized clinical trials, prospective cohort studies, retrospective cohort studies, and case series. DATA EXTRACTION: Studies were examined for the effect of the intervention on overall survival, disease-free survival, and health-related quality of life. We evaluated effects on survival in terms of number of lives saved at 10 years and average years of life saved. Costs were related to the benefits observed and modeled onto a hypothetical health care organization of 500,000 lives. RESULTS: Based on this analysis, we recommend a basic benefit plan for the detection and treatment of early breast cancer that would include the following: (1) screening mammography only for women aged 50 to 69 years; (2) choice of mastectomy or breast-conserving surgery with radiation therapy for all women with early breast cancer; (3) adjuvant therapy for all women at risk of recurrence; and (4) only clinical follow-up without routine testing for metastatic disease. CONCLUSIONS: By choosing which services they provide to specific groups of patients, providers can substantially reduce their expenses and still provide quality health benefits.

Adult↗

PubMed1994

[Value of smoking cessation, physical training and psychological interventions in secondary prevention of coronary heart disease].

Smoking, physical inactivity, and psychological traits may have substantial impacts on the development and progression of coronary heart disease. In the secondary prevention of coronary heart disease quitting smoking presents the most effective single means. In numerous studies cardiac and total mortality of ex-smokers was reduced by 40-60% when compared to continuous smokers; this effect remained stable over the years or even increased. Regular physical activity is associated with a variety of coronary and cardioprotective mechanisms. Meta-analyses of controlled studies demonstrated a significant reduction in cardiac and total mortality by rehabilitation measures which included physical training. However, this effect diminished in the following years. Psychological measures can lower cardiac risks via several mechanisms. In two major controlled secondary prevention trials interventions aiming at psychological changes such as modification of "coronary prone" type A behavior or application of "stress" reduction measures resulted in a significant decrease in the number of clinical cardiac events during the treatment phase; however, data on the long-term effects beyond the intervention period are still insufficient. In conclusion, in the secondary prevention of coronary heart disease besides strict abstention from smoking a continuous physical training and eventually psychological care in special heart groups of as many qualified patients as possible seems recommendable.

Combined Modality Therapy↗

PubMedDate not supplied

The hypertensive patient in family practice.

BACKGROUND: Hypertension is one of the commonest reasons for visits to family physicians. Left untreated, hypertension and its sequelae can lead to serious morbidity and mortality. Most hypertensive patients have essential hypertension. METHODS: MEDLINE and Index Medicus literature searches of original studies, meta-analyses, and clinical reviews were conducted for the years 1987 to the present to review the latest recommendations on the diagnosis and treatment of hypertension. Background information from articles written before 1987, accessed from cross-reference of the more recent articles, is occasionally cited. RESULTS AND CONCLUSIONS: Based on the reviewed literature, an approach to the diagnosis and treatment of hypertension for the family physician is presented with an emphasis on cost-effectiveness and nonpharmacologic treatment. Nonpharmacologic measures and lifestyle modification should always be part of the treatment plan, especially given the presence or risks of other comorbid conditions (i.e., diabetes and stroke). Coexisting conditions, side-effects, ease of adherence, cost of medication and monitoring, and anti-left ventricular hypertrophy properties should be considered in selecting a pharmaceutical agent to treat hypertension. Several areas of further research, particularly in the areas of cost-effectiveness and outcomes, are needed to refine further the treatment of hypertension.

Antihypertensive Agents↗

PubMed1994

If there is gold in the labeling index hills, are we digging in the right place?

Surrogate endpoint biomarkers (SEBs) are a necessary tool for cancer chemoprevention studies. However, the efficiency gain from using an SEB is purchased at a price. SEBs need to go through a developmental process, in which their behavior is understood in detail, before they can be used broadly in chemoprevention work. Examples of problems that need to be overcome are presented for labeling indices of cell proliferation. Since literature-based meta-analyses are not feasible for SEBs, a data archive is proposed in order to strengthen the development phase by pooling data across studies.

Anticarcinogenic Agents↗