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Kenneth F Schulz

Publications and source records attributed to Kenneth F Schulz.

At least 19 recordsLinked to original sources
PubMed2005

Twenty micrograms vs. >20 microg estrogen oral contraceptives for contraception: systematic review of randomized controlled trials.

Concern about estrogen-related adverse effects has led to progressive reductions in the estrogen dose in combination oral contraceptives (COCs). This review of randomized controlled trials tested the hypothesis that COCs containing 20 microg in terms of contraceptive effectiveness, bleeding patterns, discontinuation and side effects. Data from the 18 eligible trials conducted to date are inadequate for detecting possible differences in contraceptive effectiveness. Several COCs containing 20 microg EE resulted in higher rates of early trial discontinuation (overall and due to adverse events such as irregular bleeding) as well as increased risk of bleeding disturbances (both amenorrhea/infrequent bleeding and irregular, prolonged, frequent bleeding or breakthrough bleeding or spotting) than their higher-estrogen comparison pills. However, most trials compared COCs containing different progestin types, and changes in bleeding patterns could be related to progestin type as well as estrogen dose. While health care providers and women might select COCs containing 20 microg EE based on theoretical improvements in safety profile from the reduced dose of estrogen, no evidence is available to support this choice.

Adult↗
PubMed2005

Steroid hormones for contraception in men: systematic review of randomized controlled trials.

Male hormonal contraception has been an elusive goal. Administration of sex steroids to men can shut off sperm production through effects on the pituitary and hypothalamus. However, this approach also decreases production of testosterone, so an "add-back" therapy is needed. We conducted a systematic review of all randomized controlled trials of male hormonal contraception and azoospermia. Few significant differences emerged from these trials. Levonorgestrel implants combined with injectable testosterone enanthate (100 mg im) were significantly more effective than was levonorgestrel 125 microg po daily combined with testosterone patches [10 mg/d; odds ratio (OR) for azoospermia with the oral levonorgestrel regimen, 0.03; 95% CI, 0.00-0.29]. The addition of levonorgestrel 500 microg po daily improved the effectiveness of testosterone enanthate 100 mg im weekly by itself (OR for azoospermia with the combined regimen, 4.0; 95% CI, 1.00-15.99). Several regimens, including testosterone alone and gonadotropin-releasing hormone agonists and antagonists, had disappointing results. In conclusion, no male hormonal contraceptive is ready for clinical use. All trials published to date have been small exploratory studies. As a result, their power to detect important differences has been limited and their results have been imprecise. In addition, the definition of oligospermia has been imprecise or inconsistent in many reports. To avoid bias, future trials need to pay more attention on the methodological requirements for randomized controlled trials. Trials with adequate power would also be helpful.

Adult↗
PubMed2005

Fertility awareness-based methods for contraception: systematic review of randomized controlled trials.

CONTEXT: Fertility awareness-based (FAB) methods of family planning estimate the fertile days of the menstrual cycle whether by observing fertility signs such as cervical secretions and basal body temperature or by monitoring cycle days. The efficacy and acceptability of these methods are unclear. METHODS: We retrieved and analyzed all randomized controlled trials that examined any FAB method used for contraception. RESULTS: Because of poor methods and reporting, pregnancy rates could not be determined. A trial in Colombia found similar numbers of pregnancies among women randomized to the ovulation and symptothermal methods, but a trial in Los Angeles observed more pregnancies in the group assigned to the ovulation method. In the two American trials, recruitment of participants was unexpectedly difficult. Continuation rates were poor. CONCLUSION: Despite intensive training and ongoing support, most participants in these trials discontinued prematurely. The comparative efficacy of these methods remains unknown. However, with the ovulation and symptothermal methods, pregnancies appear to be common; method continuation rates are low.

Awareness↗
PubMed2005

The CONSORT Statement: revised recommendations for improving the quality of reports of parallel-group randomized trials 2001.

To comprehend the result of a randomized controlled trial (RCT), readers must understand its design, conduct, analysis and interpretation. That goal can be achieved only through complete transparency from authors. Despite several decades of educational efforts, the reporting of RCTs needs improvement. Investigators and editors developed the original CONSORT (Consolidated Standards of Reporting Trials) statement to help authors improve reporting by using a checklist and flow diagram. The revised CONSORT statement presented in this article incorporates new evidence and addresses some criticism of the original statement. The checklist items pertain to the content of the Title, Abstract, Introduction, Methods, Results, and Comment. The revised checklist includes 22 items selected because empirical evidence indicates that not reporting the information is associated with biased estimates of treatment effect or because the information is essential to judge the reliability or relevance of the findings. We intended the flow diagram to depict the passage or participants through an RCT. The revised flow diagram depicts information from 4 stages of a trial (enrollment, intervention allocation, follow-up and analysis). The diagram explicitly includes the number of participants, according to each intervention group, included in the primary data analysis. Inclusion of these numbers allows the reader to judge whether the authors have performed an intention-to-treat analysis. In sum, the CONSORT statement is intended to improve the reporting or an RCT, enabling readers to understand a trial's conduct and to assess the validity of its results.

Guidelines as Topic↗
PubMed2005

Surrogate end points in clinical research: hazardous to your health.

Surrogate end points in clinical research pose real danger. A surrogate end point is an outcome measure, commonly a laboratory test, that substitutes for a clinical event of true importance. Resistance to activated protein C, for example, has been used as a surrogate for venous thrombosis in women using oral contraceptives. Other examples of inappropriate surrogate end points in contraception include the postcoital test instead of pregnancy to evaluate new spermicides, breakage and slippage instead of pregnancy to evaluate condoms, and bone mineral density instead of fracture to assess the safety of depo-medroxyprogesterone acetate. None of these markers captures the effect of the treatment on the true outcome. A valid surrogate end point must both correlate with and accurately predict the outcome of interest. Although many surrogate markers correlate with an outcome, few have been shown to capture the effect of a treatment (for example, oral contraceptives) on the outcome (venous thrombosis). As a result, thousands of useless and misleading reports on surrogate end points litter the medical literature. New drugs have been shown to benefit a surrogate marker, but, paradoxically, triple the risk of death. Thousands of patients have died needlessly because of reliance on invalid surrogate markers. Researchers should avoid surrogate end points unless they have been validated; that requires at least one well done trial using both the surrogate and true outcome. The clinical maxim that "a difference to be a difference must make a difference" applies to research as well. Clinical research should focus on outcomes that matter.

Biomarkers↗
PubMed2005

Nonhormonal drugs for contraception in men: a systematic review.

UNLABELLED: Nonhormonal drugs for contraception in men may have advantages over hormonal methods. The nonhormonal methods can have more rapid onset and less interference with androgen-dependent functions. This systematic review summarizes the clinical studies evaluating nonhormonal drugs administered to men for contraception. Relevant clinical results were found for gossypol, which is derived from the cotton plant, and for extracts of Tripterygium, a plant used in Chinese traditional medicine. Randomized, controlled trials were available on the efficacy of gossypol and on the effect of gossypol on potassium levels. Gossypol had problems with low efficacy and toxicity. For Tripterygium, 2 observational studies described men who were treated for rheumatoid arthritis. Although sperm density was lower among those taking Tripterygium, later reports indicated some toxicity. Nonclinical research continues on isolates of Tripterygium. No clinical studies for contraception in men were found for nonhormonal vaccines or neem, which is also a plant used for medicinal purposes. Clinical trials studied injecting styrene maleic anhydride into the vas deferens, but no comparative data were provided. At this time, no safe and effective nonhormonal drug is available for contraception in men. TARGET AUDIENCE: Obstetricians & Gynecologists, Family Physicians. LEARNING OBJECTIVES: After completion of this article, the reader should be able to state that the number of studies concerning the use of nonhormonal drugs for male contraception are very limited, point out that the two nonhormonal drugs used to a small degree have varying results and serious side effects, and recall that there are limited clinical studies on use of vas deferens injections and vaccines in humans.

Contraceptive Agents, Male↗
PubMed2004

Combination estrogen-progestin contraceptives and body weight: systematic review of randomized controlled trials.

OBJECTIVE: Many women and clinicians believe that combination estrogen-progestin contraceptive use can lead to weight gain. This concern can deter women from starting hormonal contraception or lead to premature quitting. This review evaluated the association between combination contraceptive use and change in body weight. DATA SOURCES: The computerized databases CENTRAL, MEDLINE, EMBASE, Popline, and LILACS (from their inception to 2002) were used to conduct this review. Known investigators and manufacturers were contacted for information about other trials not discovered in the database search. METHODS OF STUDY SELECTION: All English-language, randomized controlled trials measuring weight change that were at least 3 treatment cycles in duration and that compared a combination contraceptive to a placebo or to a combination contraceptive that differed in drug, dosage, regimen, or study length were eligible for inclusion. Of the 570 reports of randomized controlled trials of eligible interventions that were identified, 42 trials were included in the systematic review. TABULATION, INTEGRATION, AND RESULTS: Two reviewers independently abstracted data from the eligible trials using a standard form. Depending on the data available, the weighted mean difference using a fixed effect model with 95% confidence intervals was calculated for the mean change in weight between baseline and posttreatment measurements or the Peto odds ratio with 95% confidence intervals was calculated by using the proportion of women who gained or lost more than a specified amount of weight. The 3 placebo-controlled, randomized trials did not find evidence supporting a causal association between combination oral contraceptives or a combination skin patch and weight gain. Most comparisons from the 40 trials that compared 2 or more combination contraceptives showed no substantial difference in weight. In addition, discontinuation of combination contraceptives because of weight gain did not differ between groups when this factor was studied. CONCLUSION: Available evidence is insufficient to determine the effect of combination contraceptives on weight, but no large effect is evident.

Adult↗
PubMed2003

The reporting of methods for reducing and detecting bias: an example from the WHO Misoprostol Third Stage of Labour equivalence randomised controlled trial.

BACKGROUND: The aim of this article is to explore ways in which selection bias and ascertainment bias can be reduced and investigated in trials, by using the example of a drug trial carried out in both developed and developing countries in hospital delivery wards. METHODS: We describe an innovative and practical design for the boxes for packing the drugs as a way of increasing the security of allocation concealment and blinding. We also assess ascertainment bias using sensitivity analyses, as some unblinding could have occurred due to a potential side effect of one of the drugs. RESULTS: The sensitivity analyses indicated that the conclusions about the relative effects of the treatments could be maintained even in the unlikely worst-case scenarios. CONCLUSIONS: Detailed description of the procedures protecting against common biases and of the assessment of ascertainment bias in this trial should allow readers to confidently appraise and interpret the results obtained. In addition, our experiences will assist others in planning trials in the future.

Developed Countries↗
PubMed2003

The CONSORT statement: revised recommendations for improving the quality of reports of parallel-group randomised trials.

To comprehend the results of a randomised controlled trial (RCT), readers must understand its design, conduct, analysis, and interpretation. That goal can be achieved only through total transparency from authors. Despite several decades of educational efforts, the reporting of RCTs needs improvement. Investigators and editors developed the original CONSORT (Consolidated Standards of Reporting Trials) statement to help authors improve reporting by use of a checklist and flow diagram. The revised CONSORT statement presented here incorporates new evidence and addresses some criticisms of the original statement. The checklist items pertain to the content of the Title, Abstract, Introduction, Methods, Results, and Discussion. The revised checklist includes 22 items selected because empirical evidence indicates that not reporting this information is associated with biased estimates of treatment effect, or because the information is essential to judge the reliability or relevance of the findings. We intended the flow diagram to depict the passage of participants through an RCT. The revised flow diagram depicts information from four stages of a trial (enrollment, intervention allocation, follow- up, and analysis). The diagram explicitly shows the number of participants, for each intervention group, included in the primary data analysis. Inclusion of these numbers allows the reader to judge whether the authors have done an intention- to-treat analysis. In sum, the CONSORT statement is intended to improve the reporting of an RCT, enabling readers to understand a trial's conduct and to assess the validity of its results.

Humans↗