Search PubMed⌕ Search

Biomedical subjects

K F Schulz

Publications and source records attributed to K F Schulz.

At least 19 recordsLinked to original sources
PubMed1995

Subverting randomization in controlled trials.

Recent empirical evidence supports the importance of adequate randomization in controlled trials. Trials with inadequate allocation concealment have been associated with larger treatment effects compared with trials in which authors reported adequate allocation concealment. While that provides empirical evidence of bias being interjected into trials, trial investigators rarely document the sensitive details of subverting the intended purpose of randomization. This article relates anonymous accounts run the gamut from simple to intricate operations, from transillumination of envelopes to searching for code in the office files of the principal investigator. They indicate that deciphering is something more frequent than a rate occurrence. These accounts prompt some methodological recommendations to help prevent deciphering. Randomized controlled trials appear to annoy human nature--if properly conducted, indeed they should.

Random Allocation↗
PubMed1995

Unbiased research and the human spirit: the challenges of randomized controlled trials.

Research by Klein and associates provides useful information on the relation between episiotomy and outcomes such as perineal trauma, but the methodologic implications of their work are especially fascinating. Physicians who participated in their randomized controlled trial (RCT) were supposed to adhere to a policy of either liberal or restrictive use of episiotomy according to the study arm to which each patient was assigned. However, some used the procedure for approximately 90% of patients regardless of allocation. Klein and associates' post-hoc study (see pages 769 to 779 of this issue) sheds light on the relation between physician attitudes and the practice of episiotomy. The author contends that the noncompliance encountered by Klein and associates reflects the fact that randomized trials are anathema to the human spirit. He offers suggestions for making RCTs more meaningful and stresses that, although RCTs are indispensible to the advancement of medical knowledge, they necessitate assiduous attention to matters of design and implementation.

Attitude of Health Personnel↗
PubMed1995

Empirical evidence of bias. Dimensions of methodological quality associated with estimates of treatment effects in controlled trials.

OBJECTIVE: To determine if inadequate approaches to randomized controlled trial design and execution are associated with evidence of bias in estimating treatment effects. DESIGN: An observational study in which we assessed the methodological quality of 250 controlled trials from 33 meta-analyses and then analyzed, using multiple logistic regression models, the associations between those assessments and estimated treatment effects. DATA SOURCES: Meta-analyses from the Cochrane Pregnancy and Childbirth Database. MAIN OUTCOME MEASURES: The associations between estimates of treatment effects and inadequate allocation concealment, exclusions after randomization, and lack of double-blinding. RESULTS: Compared with trials in which authors reported adequately concealed treatment allocation, trials in which concealment was either inadequate or unclear (did not report or incompletely reported a concealment approach) yielded larger estimates of treatment effects (P < .001). Odds ratios were exaggerated by 41% for inadequately concealed trials and by 30% for unclearly concealed trials (adjusted for other aspects of quality). Trials in which participants had been excluded after randomization did not yield larger estimates of effects, but that lack of association may be due to incomplete reporting. Trials that were not double-blind also yielded larger estimates of effects (P = .01), with odds ratios being exaggerated by 17%. CONCLUSIONS: This study provides empirical evidence that inadequate methodological approaches in controlled trials, particularly those representing poor allocation concealment, are associated with bias. Readers of trial reports should be wary of these pitfalls, and investigators must improve their design, execution, and reporting of trials.

Bias↗
PubMed1995

The cofactor effect of genital ulcers on the per-exposure risk of HIV transmission in sub-Saharan Africa.

The goal was to estimate the cofactor effect of genital ulcer disease (GUD) on the risk of HIV transmission during a single heterosexual exposure. The relation between the risk ratio observed in an epidemiological study and the per-exposure cofactor effect was investigated. Given simple assumptions, we show that observed risk ratios are expected to be very much smaller than per-exposure cofactor effects and to decrease as the observation period increases. Data from longitudinal studies of female commercial sex workers and men in Nairobi were reanalysed. The data are consistent with GUD cofactor effects per sexual exposure of 10-50 for male to female transmission, and of 50-300 for female to male transmission. Although subject to wide margins of error, these estimates indicate that GUD may be responsible for a high proportion of heterosexually acquired HIV infections in sub-Saharan Africa, supporting the potential role of STD control as an effective intervention strategy against HIV.

Africa South of the Sahara↗
PubMed1992

Randomized controlled trials of home uterine activity monitoring: a review and critique.

Home uterine activity monitoring has been proposed as an effective technique for reducing the incidence of preterm birth by early recognition of incipient labor. Five randomized controlled trials evaluating this technique have been published in peer review journals. As judged by accepted criteria for such trials, all have serious methodologic deficiencies. Four of the five trials demonstrated no significant benefit from this monitoring. Two other trials not published in peer review journals support the hypothesis that home uterine activity monitoring is no more effective than daily nursing contact. Until the efficacy of this technology has been established, home uterine activity monitoring should not be used clinically.

Evaluation Studies as Topic↗
PubMed1990

Preventing IUCD-related pelvic infection: the efficacy of prophylactic doxycycline at insertion.

Most of the small increased risk in pelvic inflammatory disease (PID) associated with the intrauterine contraceptive device (IUCD) appears to be caused by bacterial contamination of the endometrial cavity at the time of insertion. This randomized clinical trial of 1813 women in Nairobi, Kenya, assessed the effectiveness of 200 mg of doxycycline given orally at the time of insertion in reducing the occurrence of PID. The rate of this infection in the doxycycline-treated group was 31% lower than that in the placebo-treated group (1.3 and 1.9%, respectively; RR 0.69; 95% CI 0.32 to 1.5). The rate of an unplanned IUCD-related visit to the clinic was also 31% lower in the doxycycline-treated group (RR 0.69; 95% CI 0.52 to 0.91). Although the significance level (P = 0.17) for the reduction is PID does not meet the conventional standard of 0.05, the results may be suggestive of an effect. Moreover, the reduction in IUCD-related visits (P = 0.004) not only represents an important decrease in morbidity but also substantiates the reduction found for PID. Further studies are needed to corroborate these results. Consideration should be given to the prophylactic use of doxycycline at the time of IUCD insertion as an approach to preventing PID and other IUCD-related morbidity.

Adult↗
PubMed1987

Pregnancy loss, infant death, and suffering: legacy of syphilis and gonorrhoea in Africa.

Africa in the 1980s appears to be facing problems associated with syphilis and gonorrhoea during pregnancy similar in severity and magnitude to those faced by the western world in the early 1900s. From a review of published reports, the prevalence of syphilis seroreactivity in pregnant women in many parts of Africa is at least 10%. Assuming this level of seroreactivity, we estimate that 5% to 8% of all pregnancies surviving past 12 weeks will have an adverse outcome caused by syphilis, such as spontaneous abortion, perinatal or infant death, or a living infant with syphilis. Our findings on gonorrhoea during pregnancy are almost as startling. The prevalence of gonorrhoea in pregnant women in many parts of Africa is at least 10% and it approaches 20% in some areas. The incidence of gonococcal ophthalmia neonatorum in neonates appears to be between 2% and 4%. We recommend commitment of health resources to initiatives to prevent and control sexually transmitted disease in Africa and additional research into the cost effectiveness of different prevention and control approaches.

Abortion, Spontaneous↗
PubMed1985

The risk of serious complications from induced abortion: do personal characteristics make a difference?

We examined the age, gestational age, parity, race, and number of previous spontaneous and induced abortions of 82,030 women who obtained abortions at less than or equal to 24 weeks' gestation. Among these women, 342 (0.4%) had serious complications, including 130 (0.2%) with fever greater than or equal to 38 degrees C for 3 or more days, 172 (0.2%) who required transfusions, 67 (0.1%) who required unintended surgery, and three who died. Factors significantly (p less than 0.05) associated with serious complications varied by period of gestation, including previous induced abortions (adjusted relative risk = 1.57, 95% confidence interval = 1.03 to 2.40) for procedures done at less than or equal to 12 weeks' gestation, advancing age (relative risk for a 5-year increment = 1.12, 95% confidence interval = 1.01 to 1.24), and advancing gestational age (relative risk for a 2-week increment = 1.50, 95% confidence interval = 1.43 to 1.57) for procedures done at greater than 12 weeks, and greater than or equal to 1 previous delivery (relative risk = 1.34, 95% confidence interval = 1.03 to 1.75) for all gestational ages. Although Hispanic women had higher rates of complications compared with white women, data were not available to control for socioeconomic status in comparing race groups. There was no significant association between previous spontaneous abortions and serious complications. Risk patterns were similar, but not identical, when fever, operation, and transfusion were considered separately.

Abortion, Induced↗
PubMed1985

Preventing febrile complications of suction curettage abortion.

To identify risk factors for febrile complications after suction curettage abortion, we analyzed the data of 26,332 women who underwent suction curettage abortion at five participating centers in the Joint Program for the Study of Abortion, Part III, from 1975 to 1978. We defined febrile morbidity as an oral temperature of greater than or equal to 38 degrees C for 2 days or longer. The febrile morbidity rate was 0.34 per 100 abortions. We performed a multivariate analysis using a linear logistic regression model. Prophylactic antibiotics proved to be the most protective factor, reducing the rate of febrile complications to about one third that of women who received no prophylactic antibiotics (relative risk 0.36; 95% confidence interval 0.18 to 0.70). Patients who had had one or more previous births also had a significantly lower risk of febrile morbidity (relative risk 0.54; 95% confidence interval 0.33 to 0.88). Other factors did not significantly affect the febrile complication rate.

Abortion, Induced↗
PubMed1985

Hysterectomy performed within 1 year after tubal sterilization.

In the United States, approximately 650,000 women of reproductive age undergo tubal sterilization each year and some of these women later have hysterectomies. Little is known about risk factors for having hysterectomy after tubal sterilization. For examination of this issue, we analyzed data from the Collaborative Review of Sterilization, an ongoing multicenter prospective study designed to assess the safety and efficacy of female sterilization operations. In 1979 and 1980, 4002 women 15 to 44 years of age had interval tubal sterilization; of these women, 64 had hysterectomies within 15 months, which yielded a cumulative incidence of 1.6%. Women with a history of menstrual complaints, leiomyomata, ovarian cysts, or endometriosis before their tubal sterilization had an increased risk of hysterectomy, compared with women without such a history. However, 98% of women with a history of these conditions did not have a hysterectomy within 15 months after tubal sterilization. Further follow-up of these women should help to better delineate their long-term risks.

Adolescent↗
PubMed1985

The comparative safety of second-trimester abortion methods.

The comparative safety of methods used to perform second-trimester abortion is an important public health concern. Morbidity and mortality studies indicate that dilatation and evacuation (D & E) is safer than instillation abortion, which is safer than hysterotomy or hysterectomy. In the third phase of the Joint Program for the Study of Abortion, the adjusted relative risk of serious complications associated with intra-amniotic instillation of urea and prostaglandin F2 alpha (the safest abortifacient regimen) was 1.9 times that associated with D & E (95% confidence interval 1.2-3.1). Surveillance of abortion mortality in the United States from 1972 to 1981 revealed a death-to-case rate of 4.9 per 100 000 abortions associated with D & E, 9.6 with instillation methods, and over 60 with hysterotomy or hysterectomy. Little information exists on potential late sequelae of second-trimester abortion. D & E appears to be the safest method of second-trimester abortion available in the United States.

Abortion, Induced↗
PubMed1985

Morbidity and mortality from second-trimester abortions.

The comparative safety of methods used to perform second-trimester abortion is an important public health concern. Morbidity and mortality studies have indicated that dilation and evacuation (D&E) is safer than instillation abortion, which is safer than hysterotomy and hysterectomy. In the third phase of the Joint Program for the Study of Abortion, the adjusted relative risk of serious complications associated with the intraamniotic instillation of urea and prostaglandin F2 alpha (the safest abortifacient regimen) was 1.9 times that associated with D&E (95% confidence interval, 1.2-3.1). An analysis of abortion mortality in the United States from 1972 to 1981 revealed a death-to-case rate of 4.9 per 100,000 abortions associated with D&E, 9.6 with instillation methods and over 60 with hysterotomy and hysterectomy. Little information exists concerning potential late sequelae of second-trimester abortion. D&E appears to be the safest method of second-trimester abortion available in the United States.

Abortion, Induced↗
PubMed1985

Abortions that fail.

In this study of 33,090 suction curettage abortions performed at less than or equal to 12 weeks' gestation, the rate of unrecognized failed abortions was 2.3 per 1000 abortions. Women with one or more prior pregnancies and those having an abortion at less than or equal to six weeks' gestation, particularly when small suction cannulae were used, were at higher risk for this complication (relative risks of 2.2, 2.9, and 11.1, respectively). Failures were also more likely when abortions were performed by resident physicians (relative risk of 2.2) and when they were performed on women with uterine anomalies (relative risk of 90.6). Physicians can minimize the risk of failed abortion by selecting an appropriate suction cannula size and by planning the optimal time to perform the abortion. Likewise, abortions performed either by residents or on women with uterine anomalies merit extra care.

Abortion, Legal↗
PubMed1985

Safety of local versus general anesthesia for second-trimester dilatation and evacuation abortion.

In 1980, approximately 100,000 women underwent abortion by dilatation and evacuation between 13 and 24 weeks' gestation; an estimated 500 women experienced serious complications. The comparative safety of local versus general anesthesia for second-trimester dilatation and evacuation is unknown. To compare the serious complications (hemorrhage requiring transfusion, unintended major surgery, and a temperature of greater than or equal to 38 C for greater than three days), 4147 women who received general anesthesia and 5389 women who received local anesthesia at 13 centers in the United States from 1975 to 1978 were studied. Women who had a dilatation and evacuation abortion under general anesthesia had a relative risk of serious complications of 2.6 (95% confidence interval 1.4 to 4.9) compared with women who underwent dilatation and evacuation abortion under local anesthesia. Local anesthesia for second-trimester dilatation and evacuation appears to be both safer and less expensive than general anesthesia.

Abortion, Induced↗
PubMed1984

Prophylactic antibiotics for curettage abortion.

Opinion is divided as to the advisability of routine use of prophylactic antibiotics for curettage abortion. Six studies, including three randomized clinical trials, suggest that prophylaxis reduces infectious morbidity associated with curettage abortions by about one half. Three other studies, two involving prophylaxis for instillation abortions and one involving a vaginal antiseptic for curettage abortion, support the hypothesis that antimicrobial prophylaxis reduces morbidity. Tetracyclines are commonly used for this purpose. The cost of routine prophylaxis even with an expensive tetracycline would appear to be offset by the savings in direct and indirect costs. Prophylaxis may help prevent both short-term morbidity and potential late sequelae, such as ectopic pregnancy and infertility.

Abortion, Induced↗