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Results for “Randomized trial”

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PubMed1999

Randomized trial comparing interferential therapy with motorized lumbar traction and massage in the management of low back pain in a primary care setting.

STUDY DESIGN: A randomized trial designed to compare interferential therapy with motorized lumbar traction and massage management for low back pain in a primary care setting. OBJECTIVE: To measure and compare the outcome of interferential therapy and management by motorized lumbar traction and massage. SUMMARY OF BACKGROUND DATA: Management of low back pain by interferential therapy and motorized lumbar traction and massage is common in Germany. No reports of previous randomized trials for the outcome from interferential therapy were found. METHODS: Consenting patients were randomly assigned into one of two groups. A pretreatment interview was performed by the patient using a computer-based questionnaire. It also incorporated the Oswestry Disability Index and a pain visual analog scale. Management consisted of six sessions over a 2- to 3-week period. Oswestry Disability Indexes and pain visual analog scale scores also were obtained immediately after and at 3 months after treatment. RESULTS: A total of 152 patients were recruited. The two treatment groups had similar demographic and clinical baseline characteristics. The mean Oswestry Disability Index before treatment was 30 for both groups (n = 147). After treatment, this had dropped to 25, and, at 3 months, were 21 (interferential therapy) and 22 (motorized lumbar traction and massage). The mean pain visual analog scale score before treatment was 50 (interferential therapy) and 51 (motorized lumbar traction and massage). This had dropped, respectively, to 46 and 44 after treatment and to 42 and 39 at 3 months. CONCLUSIONS: This study shows a progressive fall in Oswestry Disability Index and pain visual analog scale scores in patients with low back pain treated with either-interferential therapy or motorized lumbar traction and massage. There was no difference in the improvement between the two groups at the end of treatment. Although there is evidence from several trials that traction alone is ineffective in the management of low back pain, this study could not exclude some effect from the concomitant massage.

Adult↗

PubMed2003

Acupuncture Randomized Trials (ART) in patients with chronic low back pain and osteoarthritis of the knee - design and protocols.

BACKGROUND: We report on the study design and protocols of two randomized controlled trials (Acupuncture Randomized Trials = ART) that investigate the efficacy of acupuncture in the treatment of chronic low back pain and osteoarthritis of the knee, respectively. OBJECTIVE: To investigate whether acupuncture is more efficacious than (a) no treatment or (b) minimal acupuncture in the treatment of low back pain and osteoarthritis. DESIGN: Two randomized, controlled, multicenter trials with three treatment arms and a total follow-up time of 52 weeks. SETTING: 30 practitioners and outpatient units in Germany specialized in acupuncture treatment. PATIENTS: 300 patients will be included in each study. In the low back pain trial, patients will be included according to clinical diagnosis. In the osteoarthritis pain trial, patients will be included according to the American College of Rheumatology criteria. INTERVENTIONS: Patients are randomly assigned to receive either (1) semi-standardized acupuncture (150 patients), (2) minimal acupuncture at non-acupuncture points (75 patients), or (3) no treatment for two months followed by semi-standardized acupuncture (75 patients, waiting list control). Acupuncture treatment consists of 12 sessions per patient over a period of 8 weeks. MAIN OUTCOME MEASURE: The main outcome measure is the difference between baseline and the end of the 8-week treatment period in the following parameters: pain intensity as measured by a visual analogue scale (VAS; 0-100 mm) in the low back pain trial and by the Western Ontario and McMaster Universities Osteoarthritis Score (WOMAC) in the osteoarthritis trial. OUTLOOK: The results of these two studies (available in 2004) will provide health care providers and policy makers with the information needed to make scientifically sound assessments of acupuncture therapy.

Acupuncture Therapy↗

PubMed2005

Prostate Cancer Screening in the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial: findings from the initial screening round of a randomized trial.

BACKGROUND: The benefit of screening for prostate cancer using prostate-specific antigen (PSA) testing and digital rectal examination (DRE) is uncertain and is under evaluation in a randomized prospective trial, the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial. Although the final results are several years away, the initial round of screening is complete. We describe the population enrolled in the PLCO trial, their baseline PSA and DRE screening results, and diagnostic follow-up results during the first year of follow-up. METHODS: A total of 38,350 men were randomly assigned to the screening arm of the PLCO trial from November 1993 through June 2001. Men were advised to seek diagnostic follow-up from their primary care provider if their DRE was suspicious for cancer and/or if their serum PSA level was higher than 4 ng/mL. PLCO trial staff obtained records related to diagnostic follow-up. RESULTS: Compliance with both screening tests was high (more than 89%). At screening, 7.5% of men had a positive DRE (i.e., suspicious for cancer) and 7.9% had a PSA level higher than 4 ng/mL. Of the men with positive screening tests, 74.2% underwent additional diagnostic testing, and 31.5% underwent a prostatic biopsy within 1 year. Overall, 1.4% of the men in the screening arm were diagnosed with prostate cancer, the majority of whom had clinically localized cancer. These compliance, biopsy, and cancer detection rates appear to be representative of contemporary practice patterns. CONCLUSION: The PLCO trial is evaluating PSA- and DRE-based screening for prostate cancer in a clinically valid manner. Whether such screening will result in a reduction of prostate cancer mortality cannot be answered until the randomized comparison is completed.

Aged↗

PubMed2006

Recruitment and enrollment of rural and urban medically underserved elderly into a randomized trial of telemedicine case management for diabetes care.

Our goal was to identify reasons for enrollment or refusal to participate in a randomized trial of telemedicine case management of diabetes. We performed a prospective survey of participants and non-participants during recruitment for the Informatics for Diabetes Education and Telemedicine (IDEATel) study, a randomized trial of telemedicine case management of diabetes mellitus in medically underserved elderly. There were two recruitment areas: urban New York City, and rural upstate New York. A Participant Questionnaire (PQ) was administered at the baseline IDEATel visit, and a Non-Participant Questionnaire (NPQ) was administered during the recruitment telephone call. Both questionnaires listed possible responses; subjects could choose more than one response or give their own. Of 1,660 IDEATel participants, 99.7% completed the PQ. Most frequent reason for participation was the belief that the technology could help them (52% and 42% of urban and rural respondents, respectively). Of the 2,231 subjects refusing participation, 28% answered the NPQ (90% of respondents were from rural area). Most frequent reasons not to participate in the rural area were being too busy (23%), and discomfort with the technology (22%), and in the urban area the belief that the technology could not help them (71%), discomfort with it (52%), and not liking to participate in studies (52%). In multivariate analysis (rural respondents only), knowing how to use a computer was an independent predictor of participation (p < 0.001). In conclusion, perceptions and beliefs regarding technology, including the expectation to benefit from it, played an important role in the decision to participate.

Aged↗

PubMed1989

The effectiveness of chemotherapy for treatment of high grade astrocytoma in children: results of a randomized trial. A report from the Childrens Cancer Study Group.

Fifty-eight patients with high-grade astrocytoma were treated by members of the Childrens Cancer Study Group in a prospective randomized trial designed to study the effectiveness of chemotherapy as an adjuvant to standard surgical treatment and radiotherapy. Following surgical therapy, patients were assigned randomly to radiotherapy with or without chemotherapy consisting of chloroethyl-cyclohexyl nitrosourea, vincristine, and prednisone. Treatment with chemotherapy prolonged survival and event-free survival. Five-year event-free survival was 46% for patients in the radiotherapy and chemotherapy group, and 18% for patients in the radiotherapy-alone group. Five-year survival was similarly improved. The differences in outcome due to treatment were statistically significant after correcting for imbalances in important prognostic factors (event-free survival, p = 0.026; survival, p = 0.067). The presence of mitoses or necrosis in the tumor specimen was associated with poorer outcome. Patients whose initial surgery was limited to biopsy, and patients with basal ganglia lesions, also had significantly worse outcome. Chemotherapy administered at the time of recurrence in a small number of patients did not produce any long-term survivors. This study is to our knowledge the only randomized trial to investigate effectiveness of chemotherapy in the treatment of high-grade astrocytoma in children.

Adolescent↗

PubMed1985

Treatment with histamine H2 antagonists in acute upper gastrointestinal hemorrhage. Implications of randomized trials.

Histamine H2 antagonists are widely used in treating patients with hematemesis and melena, despite the lack of reliable evidence of benefit from any of the randomized trials, considered separately. Examination of the data from all 27 available randomized trials, in which over 2500 patients were entered, suggests that treatment may reduce the rates of rebleeding, surgery, and death by about 10, 20, and 30 per cent, respectively, although these results were only marginally significant for surgery and death. Any benefit appeared to be confined to patients with bleeding gastric ulcers, but since this subgroup analysis was prompted by preliminary examination of the data in some of the individual trials reviewed here, it should be treated with particular caution. The implications of this overview are that treatment with histamine H2 antagonists appears to be moderately promising, but its effects on important end points, such as death, still need to be assessed reliably. Prevention of "only" about 20 per cent of all deaths could well be worthwhile, for the condition is common, and the treatment widely practicable. To detect such a moderate effect reliably, however, might require the randomization of 10,000 patients (or more), which would be possible only in an extremely simple multicenter collaborative trial.

Acute Disease↗

PubMed2004

[The cluster-randomized trial].

Within the framework of a clinical trial, one is sometimes brought to randomize groups of subjects rather than the subjects themselves. This type of experimental design has methodological consequences of importance (in particular biostatistical consequences) and can limit the extrapolation of the results. A cluster randomized trial is thus justified only if the context or the question of interest imposes it and biostatistical issues have then to be handled in a rigorous way.

Biometry↗

PubMed1994

Muscarinic antagonists in the treatment of acquired pendular and downbeat nystagmus: a double-blind, randomized trial of three intravenous drugs.

We performed a double-blind, randomized trial of intravenous scopolamine, benztropine, and glycopyrrolate in 7 patients with acquired nystagmus and oscillopsia. Five patients had pendular nystagmus and 2, downbeat nystagmus. We recorded eye movements with a magnetic search coil technique and tested visual acuity and motion perception before and after administration of each drug. Scopolamine reduced nystagmus in all patients. Benztropine was moderately effective and glycopyrrolate had a negligible impact. Visual acuity improved only with scopolamine; motion discrimination and oscillopsia improved significantly with scopolamine and benztropine. Pendular and downbeat nystagmus respond to intravenous antagonists of central muscarinic receptors.

Adult↗

PubMed1996

Operative vs. nonoperative treatment of intra-articular fractures of the calcaneus: a prospective randomized trial.

Thirty patients with displaced, intra-articular calcaneus fractures were randomized to operative or nonoperative treatment. All patients had two or three major articular fragments of the posterior facet (Sanders type II or III). Nonoperative treatment included early mobilization and delayed weightbearing. Operative treatment involved open reduction and rigid internal fixation with a plate and screws through an extensile, L-shaped lateral approach followed by early mobilization and delayed weightbearing. Fifteen operative patients were evaluated at an average of 17 months follow-up and 11 nonoperative patients were seen at 14 months average follow-up. In the operative group, there were 7 excellent results, 5 good results, 2 fair results, and 1 poor result, and in the nonoperative group there was 1 excellent result, 3 good results, 1 fair result, and 6 poor results (difference significant as P < 0.01). A functional scoring system of 0-100 points was developed based upon the responses to an outcome assessment questionnaire. The average functional score for the operative group was far superior at 86.7, compared with 55.0 for the nonoperative group (P < 0.0001). Subtalar range of motion averaged 20 degrees for the operative group and 17 degrees for the nonoperative group with pain on extremes of motion of 25% of the operative patients compared with 100% of the nonoperative patients. This study is the first prospective, randomized trial to demonstrate the superior results of current operative treatment with early mobilization compared with nonoperative treatment.

Adult↗

PubMed1994

MACOP-B versus ProMACE-MOPP in the treatment of advanced diffuse non-Hodgkin's lymphoma: results of a prospective randomized trial by the non-Hodgkin's Lymphoma Cooperative Study Group.

PURPOSE: The aim of our study was to compare in a multicentric randomized trial two regimens widely used in the treatment of advanced-stage intermediate- to high-grade non-Hodgkin's lymphoma and to assess whether a third-generation regimen (methotrexate with leucovorin, doxorubicin, cyclophosphamide, vincristine, prednisone, and bleomycin [MACOP-B]) was superior to a second-generation regimen (procarbazine, methotrexate with leucovorin, doxorubicin, cyclophosphamide, and etoposide [ProMACE-MOPP]). PATIENTS AND METHODS: Between January 1987 and August 1991, 221 patients with diffuse intermediate- to high-grade non-Hodgkin's lymphoma (Working Formulation groups F, G, H, and K), stage II bulky (> 10 cm), III, or IV, were randomized by the Non-Hodgkin's Lymphoma Cooperative Study Group (NHLCSG) to receive ProMACE-MOPP for six cycles or MACOP-B for 12 weeks. Survival, progression-free survival, and disease-free survival were determined, and multivariate analysis of prognostic factors was performed. RESULTS: In the two groups of patients, there was no significant difference in terms of complete remission (CR) rate (49.1% with ProMACE-MOPP and 52.3% with MACOP-B), 3-year overall survival rate (45.2% with PROMACE-MOPP and 52.3% with MACOP-B), and 3-year progression-free survival rate (36.4% with ProMACE-MOPP and 36.1% with MACOP-B). In terms of toxicity, no significantly greater toxicity occurred in either arm. Overall toxicity was acceptable. The most frequent side effects were grade II through IV leukopenia, infection, mucositis, and anemia. Treatment-related deaths were equally distributed. CONCLUSION: No significant differences in terms of efficacy and/or toxicity between ProMACE-MOPP and MACOP-B are evident. These results are consistent with recent randomized trials showing that the new-generation aggressive regimens are no better than previous ones.

Adolescent↗

PubMed1983

Randomized trial of 3 different regimens of combination chemotherapy in patients receiving simultaneously a hormonal treatment for advanced breast cancer.

We report the results of a randomized trial carried out by the Swiss Group for Clinical Cancer Research (SAKK) and in which 230 patients with advanced breast cancer receiving concurrently a hormonal treatment (oophorectomy for pre- and tamoxifen for postmenopausal women) were randomly allocated to three different regimens of combination chemotherapy. The therapeutic results registered with the two more intensive combinations (LMP/FVP and LMFP/ADM) were similar with regard to response rates, time to progression and survival. The patients receiving the low-dose chemotherapy lmfp showed a statistically significant lower response rate (32%, P less than 0.001) and a shorter survival (P = 0.03) than the results observed in patients treated with the two other regimens. This difference was particularly pronounced, at least regarding survival, in the following subgroups: postmenopausal women, patients with a poor performance status, dominant visceral lesions, two sites of disease and a disease-free interval longer than 12 months. Patients with bony metastases as dominant lesion fared similarly with all three regimens of chemotherapy. This latter subset of advanced breast cancer patients should probably be spared too intensive cytotoxic treatment. This is, to our knowledge, the first report of a randomized trial showing an evident correlation between response rate and survival in various subgroups of patients with advanced breast cancer treated with different chemotherapeutic regimens.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1990

Review of randomized trials of homoeopathy.

The present review covers forty published randomized trials in which the results of a homoeopathic treatment were compared to those of a standard treatment, a placebo, or no treatment at all. These trials were identified after an extensive search through the literature. They cover a wide range of pathologies. Most were double-blind and used subjective and/or multiple endpoints. The median number of patients per group was 28. The analysis only included all the randomized patients in one third of the trials. In our opinion, the results do not provide acceptable evidence that homoeopathic treatments are effective.

Double-Blind Method↗

PubMed1994

Screening for the compromised fetus: a randomized trial of umbilical artery velocimetry in unselected pregnancies.

OBJECTIVE: Meta-analysis of randomized trials of Doppler ultrasonography in high-risk pregnancies has showed reduced mortality rates among normally formed fetuses. This trial addressed the impact on outcome of umbilical artery velocimetry in a nonselected population (i.e., as a screening test in low-risk and high-risk pregnancies). STUDY DESIGN: A randomized, controlled trial with Doppler ultrasonographic investigation was performed at two gestational age windows: 26 to 30 weeks and 34 to 36 weeks. The 2986 women were randomly allocated to revealed or concealed groups in which the Doppler results were either made available or not made available to clinicians; 1056 women were studied at only the first window, 544 at only the second, and 1386 at both. RESULTS: There were no significant differences between groups in antenatal admissions to hospital, preterm deliveries, rates of cesarean section, admission to the neonatal unit, and need for assisted ventilation. There was, however, a trend toward fewer stillbirths in the "revealed" group (three vs eight, odds ratio 0.34, confidence interval 0.10 to 1.07). CONCLUSIONS: The incidence of stillbirths was reduced by more than half in the Doppler-revealed group, but the confidence intervals were wide and these findings could be compatible with chance.

Adult↗

PubMed2007

Improved spontaneous erectile function in men with mild-to-moderate arteriogenic erectile dysfunction treated with a nightly dose of sildenafil for one year: a randomized trial.

AIM: To test the hypothesis that sildenafil (50 mg nightly for one year) can improve spontaneous erectile function (EF) in men with mild-to-moderate arteriogenic erectile dysfunction (ED) responsive to erectogenic treatment. METHODS: In a prospective open-label trial, 112 men with ED were randomized to sildenafil 50 mg nightly or sildenafil 50 or 100 mg as needed for 12 months, followed by one-month and 6-month non-medicated periods. Non-randomized, non-medicated men with ED were also assessed. The EF domain of the International Index of Erectile Function (IIEF EF) and the peak systolic velocity (PSV) of penile cavernous arteries were used to measure the efficacy. RESULTS: After sildenafil treatment and a subsequent non-medicated month, IIEF EF was normal in 29 of 48 (60.4%, 95% confidence interval [CI]: 45.3-74.2%) of the nightly group vs. 4 of 49 (8.2%, 95% CI: 2.3-19.6%) of the as-needed group. PSV improved by 11.2 cm/s (95% CI: 4.7-21.4; P=0.012) in the nightly group but only by 3.4 cm/s (-5.1-14.7; P=0.435) in the as-needed group. IIEF EF normalized in 1 of 18 (5.6%, 95% CI: 0.1-27.3%) non-medicated men and the PSV declined slightly. Six months after treatment, the IIEF EF remained normal and PSV was stabilized in most (28/29, 97%) nightly group men who had initially normalized. CONCLUSION: Sildenafil nightly for one year resulted in ED regression that persisted well beyond the end of treatment, so that spontaneous EF was characterized as normal on the IIEF in most men. The results from this open-label, randomized trial warrant verification under double-blind, placebo-controlled conditions.

Adult↗

PubMed2001

Double-blind randomized trial of mifepristone in combination with vaginal gemeprost or misoprostol for induction of abortion up to 63 days gestation.

BACKGROUND: Gemeprost and misoprostol are two of the most widely used prostaglandins in combination with mifepristone for medical abortion in early pregnancy. However, the efficacy and side-effects of those two drugs given vaginally have not been assessed in a randomized trial. METHODS: Randomized double-blind controlled trial involving 999 women undergoing an abortion at gestational age < or =63 days who received either 0.5 mg gemeprost (group I, n = 499) or 800 microg misoprostol (group II, n = 500) vaginally approximately 48 h after taking 200 mg mifepristone by mouth. The rate of complete abortion and the side-effects were compared between the groups. RESULTS: A total of 89 cases was excluded from full analysis of outcome because either they aborted after mifepristone alone (n = 2), had an ectopic pregnancy (n = 1), or because the outcome was uncertain as they failed to attend their follow-up appointment (n = 86). The rate of complete abortion was very high (>95%) in both groups but significantly higher after treatment with misoprostol than with gemeprost [436/453 (98.7%) versus 451/457 (96.2%), P = 0.019, difference 2.5%, confidence interval 0.4-4.7%] and there were fewer ongoing pregnancies (n = 1 versus n = 8, P < 0.018). Surgical intervention rose significantly with gestation in women who received gemeprost (P < 0.03) but not with misoprostol. The incidence of side-effects such as diarrhoea (13.7 versus 16.4%) and vomiting (27.8 versus 29.7%) was similar in women who received misoprostol or gemeprost respectively, as was the duration and amount of bleeding. CONCLUSIONS: (i) Both regimens using a reduced dose of mifepristone are highly effective methods of inducing abortion in early pregnancy; (ii) vaginal misoprostol is the preferred prostaglandin because it is it is associated with fewer failures than low-dose gemeprost, particularly at gestation > or =49 days.

Abortifacient Agents, Nonsteroidal↗

PubMed2004

A randomized trial among women with heavy menstruation -- impact of a decision aid on treatment outcomes and costs.

OBJECTIVE: To evaluate the effects of a decision aid for menorrhagia on treatment outcomes and costs over a 12-month follow-up. DESIGN: Randomized trial and pre-trial prospective cohort study. SETTING AND PARTICIPANTS: Gynaecology outpatient clinics in 14 Finnish hospitals, 363 (randomized trial) plus 206 (cohort study) patients with menorrhagia. INTERVENTION: A decision aid booklet explaining menorrhagia and treatment options, mailed to patients before their first clinic appointment. MAIN OUTCOME MEASURES: Health related quality of life, psychological well-being, menstrual symptoms, satisfaction with treatment outcome, use and cost of health care services. RESULTS: All study groups experienced overall improvement in health-related quality of life, anxiety, and psychosomatic and menstrual symptoms, but not in sexual life. Treatment in the intervention group was more active than in the control group, with more frequent course of medication and less undecided treatments. However, there were no marked disparities in health outcomes, satisfaction with treatment outcome and costs. Total costs (including productivity loss) per woman because of menorrhagia over the 12-month follow-up were 2760 and 3094 in the intervention and control group, respectively (P = 0.1). The pre-trial group also had a significantly lower rate of uterus saving surgery compared with the control group, but no difference in costs because of menorrhagia treatment. CONCLUSION: Despite some differences in treatment courses, a decision aid for menorrhagia in booklet form did not increase the use of health services or treatment costs, nor had it impact on health outcomes or satisfaction with outcome of treatment.

Adult↗

PubMed2003

Composite outcomes in randomized trials: greater precision but with greater uncertainty?

Composite outcomes, in which multiple end points are combined, are frequently used as primary outcome measures in randomized trials and are often associated with increased statistical efficiency. However, such measures may prove challenging for the interpretation of results. In this article, we examine the use of composite outcomes in major clinical trials, assess the arguments for and against them, and provide guidance on their application and reporting. To assess incidence and quality of reporting, we systematically reviewed the use of composite end points in clinical trials in Annals of Internal Medicine, BMJ, Circulation, Clinical Infectious Diseases, Journal of the American College of Cardiology, JAMA, Lancet, New England Journal of Medicine, and Stroke from 1997 through 2001 using a sensitive search strategy. We selected for review 167 original reports of randomized trials (with a total of 300 276 patients) that included a composite primary outcome that incorporated all-cause mortality. Sixty-three trials (38%) were neutral both for the primary end point and the mortality component. Sixty trials (36%) reported significant results for the primary outcome measure but not for the mortality component. Only 6 trials (4%) were significant for the mortality component but not for the primary composite outcome, whereas 19 trials (11%) were significant for both. Twenty-two trials (13%) were inadequately reported. Our review suggests that reporting of composite outcomes is generally inadequate, implying that the results apply to the individual components of the composite outcome rather than only to the overall composite. Current guidelines for the undertaking and reporting of clinical trials could be revised to reflect the common use of composite outcomes in clinical trials.

Data Interpretation, Statistical↗

PubMed2003

Anticoagulation therapy for stroke prevention in atrial fibrillation: how well do randomized trials translate into clinical practice?

CONTEXT: Warfarin has been shown to be highly efficacious for preventing thromboembolism in atrial fibrillation in randomized trials, but its effectiveness and safety in clinical practice is less clear. OBJECTIVE: To evaluate the effect of warfarin on risk of thromboembolism, hemorrhage, and death in atrial fibrillation within a usual care setting. DESIGN: Cohort study assembled between July 1, 1996, and December 31, 1997, and followed up through August 31, 1999. SETTING: Large integrated health care system in Northern California. PATIENTS: Of 13,559 adults with nonvalvular atrial fibrillation, 11,526 were studied, 43% of whom were women, mean age 71 years, with no known contraindications to anticoagulation at baseline. MAIN OUTCOMES: Ischemic stroke, peripheral embolism, hemorrhage, and death according to warfarin use and comorbidity status, as determined by automated databases, review of medical records, and state mortality files. RESULTS: Among 11,526 patients, 397 incident thromboembolic events (372 ischemic strokes, 25 peripheral embolism) occurred during 25,341 person-years of follow-up, and warfarin therapy was associated with a 51% (95% confidence interval [CI], 39%-60%) lower risk of thromboembolism compared with no warfarin therapy (either no antithrombotic therapy or aspirin) after adjusting for potential confounders and likelihood of receiving warfarin. Warfarin was effective in reducing thromboembolic risk in the presence or absence of risk factors for stroke. A nested case-control analysis estimated a 64% reduction in odds of thromboembolism with warfarin compared with no antithrombotic therapy. Warfarin was also associated with a reduced risk of all-cause mortality (adjusted hazard ratio, 0.69; 95% CI, 0.61-0.77). Intracranial hemorrhage was uncommon, but the rate was moderately higher among those taking vs those not taking warfarin (0.46 vs 0.23 per 100 person-years, respectively; P =.003, adjusted hazard ratio, 1.97; 95% CI, 1.24-3.13). However, warfarin therapy was not associated with an increased adjusted risk of nonintracranial major hemorrhage. The effects of warfarin were similar when patients with contraindications at baseline were analyzed separately or combined with those without contraindications (total cohort of 13,559). CONCLUSIONS: Warfarin is very effective for preventing ischemic stroke in patients with atrial fibrillation in clinical practice while the absolute increase in the risk of intracranial hemorrhage is small. Results of randomized trials of anticoagulation translate well into clinical care for patients with atrial fibrillation.

Aged↗