Combined oral contraceptive pill for primary dysmenorrhoea.

BACKGROUND: Dysmenorrhoea (painful menstrual cramps) is common and a major cause of pain in women. Combined oral contraceptives (OCPs) are often used in the management of primary dysmenorrhoea, but there is a need for reporting the benefits and harms. Primary dysmenorrhoea is defined as painful menstrual cramps without pelvic pathology. OBJECTIVES: To evaluate the benefits and harms of combined oral contraceptive pills for the management of primary dysmenorrhoea. SEARCH METHODS: We used standard, extensive Cochrane search methods. The latest search date 28 March 2023. SELECTION CRITERIA: We included randomised controlled trials (RCTs) comparing all combined OCPs with other combined OCPs, placebo, or management with non-steroidal anti-inflammatory drugs (NSAIDs). Participants had to have primary dysmenorrhoea, diagnosed by ruling out pelvic pathology through pelvic examination or ultrasound. DATA COLLECTION AND ANALYSIS: We used standard methodological procedures recommended by Cochrane. The primary outcomes were pain score after treatment, improvement in pain, and adverse events. MAIN RESULTS: We included 21 RCTs (3723 women). Eleven RCTs compared combined OCP with placebo, eight compared different dosages of combined OCP, one compared two OCP regimens with placebo, and one compared OCP with NSAIDs. OCP versus placebo or no treatment OCPs reduce pain in women with dysmenorrhoea more effectively than placebo. Six studies reported treatment effects on different scales; the result can be interpreted as a moderate reduction in pain (standardised mean difference (SMD) -0.58, 95% confidence interval (CI) -0.74 to -0.41; I² = 28%; 6 RCTs, 588 women; high-quality evidence). Six studies also reported pain improvement as a dichotomous outcome (risk ratio (RR) 1.65, 95% CI 1.29 to 2.10; I² = 69%; 6 RCTs, 717 women; low-quality evidence). The data suggest that in women with a 28% chance of improvement in pain with placebo or no treatment, the improvement in women using combined OCP will be between 37% and 60%. Compared to placebo or no treatment, OCPs probably increase the risk of any adverse events (RR 1.31, 95% CI 1.20 to 1.43; I² = 79%; 7 RCTs, 1025 women; moderate-quality evidence), and may also increase the risk of serious adverse events (RR 1.77, 95% CI 0.49 to 6.43; I² = 22%; 4 RCTs, 512 women; low-quality evidence). Women who received OCPs had an increased risk of irregular bleeding compared to women who received placebo or no treatment (RR 2.63, 95% CI 2.11 to 3.28; I² = 29%; 7 RCTs, 1025 women; high-quality evidence). In women with a risk of irregular bleeding of 18% if using placebo or no treatment, the risk would be between 39% and 60% if using combined OCP. OCPs probably increase the risk of headaches (RR 1.51, 95% CI 1.11 to 2.04; I² = 44%; 5 RCTs, 656 women; moderate-quality evidence), and nausea (RR 1.64, 95% CI 1.17 to 2.30; I² = 39%; 8 RCTs, 948 women; moderate-quality evidence). We are uncertain of the effect of OCP on weight gain (RR 1.83, 95% CI 0.75 to 4.45; 1 RCT, 76 women; low-quality evidence). OCPs may slightly reduce requirements for additional medication (RR 0.63, 95% CI 0.40 to 0.98; I² = 0%; 2 RCTs, 163 women; low-quality evidence), and absence from work (RR 0.63, 95% CI 0.41 to 0.97; I² = 0%; 2 RCTs, 148 women; low-quality evidence). One OCP versus another OCP Continuous use of OCPs (no pause or inactive tablets after the usual 21 days of hormone pills) may reduce pain in women with dysmenorrhoea more effectively than the standard regimen (SMD -0.73, 95% CI -1.13 to 0.34; 2 RCTs, 106 women; low-quality evidence). There was insufficient evidence to determine if there was a difference in pain improvement between ethinylestradiol 20 µg and ethinylestradiol 30 µg OCPs (RR 1.06, 95% CI 0.65 to 1.74; 1 RCT, 326 women; moderate-quality evidence). There is probably little or no difference between third- and fourth-generation and first- and second-generation OCPs (RR 0.99, 95% CI 0.93 to 1.05; 1 RCT, 178 women; moderate-quality evidence). The standard regimen of OCPs may slightly increase the risk of any adverse events over the continuous regimen (RR 1.11, 95% CI 1.01 to 1.22; I² = 76%; 3 RCTs, 602 women; low-quality evidence), and probably increases the risk of irregular bleeding (RR 1.38, 95% CI 1.14 to 1.69; 2 RCTs, 379 women; moderate-quality evidence). Due to lack of studies, it is uncertain if there is a difference between continuous and standard regimen OCPs in serious adverse events (RR 0.34, 95% CI 0.01 to 8.24; 1 RCT, 212 women), headaches (RR 0.94, 95% CI 0.50 to 1.76; I² = 0%; 2 RCTs, 435 women), or nausea (RR 1.08, 95% CI 0.51 to 2.30; I² = 23%; 2 RCTs, 435 women) (all very low-quality evidence). We are uncertain if one type of OCP reduces absence from work more than the other (RR 1.12, 95% CI 0.64 to 1.99; 1 RCT, 445 women; very low-quality evidence). OCPs versus NSAIDs There were insufficient data to determine whether OCPs were more effective than NSAIDs for pain (mean difference -0.30, 95% CI -5.43 to 4.83; 1 RCT, 91 women; low-quality evidence). The study did not report on adverse events. AUTHORS' CONCLUSIONS: OCPs are effective for treating dysmenorrhoea, but they cause irregular bleeding, and probably headache and nausea. Long-term effects were not covered in this review. Continuous use of OCPs was probably more effective than the standard regimen but safety should be ensured with long-term data. Due to lack of data, we are uncertain whether NSAIDs are better than OCPs for treating dysmenorrhoea.

Iron supplements in pregnant women with normal iron status: A systematic review and meta-analysis.

INTRODUCTION: Effects of daily iron supplementation in iron replete pregnancy are unclear. This systematic review aimed to assess benefits and harms of oral iron supplements in pregnant women without anemia and iron deficiency. MATERIAL AND METHODS: We predefined and registered a protocol in PROSPERO (CRD42020186210) and performed the review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology. We searched for randomized clinical trials (RCTs) and observational studies comparing daily oral iron supplementation with no iron supplements in non-anemic iron replete pregnant women. Searches were conducted in MEDLINE (by PubMed), EMBASE (by OVID), Cochrane Library, and ClinicalTrials.gov from inception to September 2022 without language restrictions. Two authors independently screened records, extracted data, and assessed risk of bias using the revised Cochrane risk of bias tool (RoB2). One author read full-texts, assessed certainty of evidence by GRADE and conducted meta-analyses using a random-effects model. Primary outcomes included iron deficiency anemia, iron deficiency, hemoglobin >130 g/L, elevated iron status, small for gestational age newborns, low birthweight newborns, preterm birth, and congenital anomalies. RESULTS: Eight RCTs (2822 women) but no observational studies were eligible for inclusion. Daily oral iron supplementation in pregnancy probably reduces iron deficiency anemia at term (risk ratio [RR]: 0.51, 95% confidence interval [CI]: 0.38-0.70; 4 RCTs, 1670 women; I2 = 13%; moderate-certainty evidence) and the incidence of low birthweight babies (RR: 0.30, 95% CI: 0.13-0.68; 2 RCTs, 361 infants; I2 = 0%; moderate-certainty evidence). In addition, it may reduce iron deficiency at term (RR: 0.74, 95% CI: 0.60-0.92; 4 RCTs, 1663 women; I2 = 58%; low-certainty evidence) and the incidence of small for gestational age babies (RR: 0.39, 95% CI: 0.17-0.86; 1 RCT, 213 infants; I2 not estimable; low-certainty evidence). CONCLUSIONS: Daily iron supplementation in iron replete non-anemic pregnant women probably reduces the risk of maternal iron deficiency anemia at term and low birthweight.

Industry sponsorship and research outcome.

BACKGROUND: Clinical research affecting how doctors practice medicine is increasingly sponsored by companies that make drugs and medical devices. Previous systematic reviews have found that pharmaceutical-industry sponsored studies are more often favorable to the sponsor's product compared with studies with other sources of sponsorship. A similar association between sponsorship and outcomes have been found for device studies, but the body of evidence is not as strong as for sponsorship of drug studies. This review is an update of a previous Cochrane review and includes empirical studies on the association between sponsorship and research outcome. OBJECTIVES: To investigate whether industry sponsored drug and device studies have more favorable outcomes and differ in risk of bias, compared with studies having other sources of sponsorship. SEARCH METHODS: In this update we searched MEDLINE (2010 to February 2015), Embase (2010 to February 2015), the Cochrane Methodology Register (2015, Issue 2) and Web of Science (June 2015). In addition, we searched reference lists of included papers, previous systematic reviews and author files. SELECTION CRITERIA: Cross-sectional studies, cohort studies, systematic reviews and meta-analyses that quantitatively compared primary research studies of drugs or medical devices sponsored by industry with studies with other sources of sponsorship. We had no language restrictions. DATA COLLECTION AND ANALYSIS: Two assessors screened abstracts and identified and included relevant papers. Two assessors extracted data, and we contacted authors of included papers for additional unpublished data. Outcomes included favorable results, favorable conclusions, effect size, risk of bias and whether the conclusions agreed with the study results. Two assessors assessed risk of bias of included papers. We calculated pooled risk ratios (RR) for dichotomous data (with 95% confidence intervals (CIs)). MAIN RESULTS: Twenty-seven new papers were included in this update and in total the review contains 75 included papers. Industry sponsored studies more often had favorable efficacy results, RR: 1.27 (95% CI: 1.17 to 1.37) (25 papers) (moderate quality evidence), similar harms results RR: 1.37 (95% CI: 0.64 to 2.93) (four papers) (very low quality evidence) and more often favorable conclusions RR: 1.34 (95% CI: 1.19 to 1.51) (29 papers) (low quality evidence) compared with non-industry sponsored studies. Nineteen papers reported on sponsorship and efficacy effect size, but could not be pooled due to differences in their reporting of data and the results were heterogeneous. We did not find a difference between drug and device studies in the association between sponsorship and conclusions (test for interaction, P = 0.98) (four papers). Comparing industry and non-industry sponsored studies, we did not find a difference in risk of bias from sequence generation, allocation concealment, follow-up and selective outcome reporting. However, industry sponsored studies more often had low risk of bias from blinding, RR: 1.25 (95% CI: 1.05 to 1.50) (13 papers), compared with non-industry sponsored studies. In industry sponsored studies, there was less agreement between the results and the conclusions than in non-industry sponsored studies, RR: 0.83 (95% CI: 0.70 to 0.98) (six papers). AUTHORS' CONCLUSIONS: Sponsorship of drug and device studies by the manufacturing company leads to more favorable efficacy results and conclusions than sponsorship by other sources. Our analyses suggest the existence of an industry bias that cannot be explained by standard 'Risk of bias' assessments.

Surgery versus conservative management of endometriomas in subfertile women. A systematic review.

INTRODUCTION: Endometriomas are present in up to 44% of all women with endometriosis and have a detrimental effect on fertility. However, it is controversial whether endometriomas should be surgically removed before assisted reproduction technology. Our purpose was to evaluate whether surgical stripping of endometriomas in subfertile women improves the chance of a live birth. Secondary outcomes were impact on ovarian reserve and pain. MATERIAL AND METHODS: We conducted a systematic review and meta-analysis with results reported in accordance to the PRISMA guidelines. A summary of findings table was developed using GRADE. We searched Medline and Embase. Two reviewers performed the screening. RESULTS: Of 686 manuscripts, we included one randomized controlled trial and nine retrospective cohort studies, mostly of low quality. The odds ratio for live birth after surgery [compared with conservative management before in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI)] was 0.87 (95% CI 0.64-1.18, six studies, I2  = 3%; ⨁◯◯◯, VERY LOW quality). The mean difference of antral follicle count was -2.09 (95% CI -4.84 to 0.67, four studies). No difference was observed regarding antral follicle count between the two groups (MD -2.09, 95% CI -4.84 to 0.67, four studies, ⨁◯◯◯, VERY LOW quality). Pain outcome was not reported in the included studies. CONCLUSION: The very low quality evidence suggests no difference in odds ratio of live birth between women who underwent surgery for endometriomas before IVF/ICSI compared with conservative management. Further high quality studies are needed, but due to a lack of convincing evidence favoring surgery, we recommend considering conservative treatment if the only indication is subfertility.

Sulphonylurea monotherapy for patients with type 2 diabetes mellitus.

BACKGROUND: Type 2 diabetes mellitus (T2DM) is a growing health problem worldwide. Whether sulphonylureas show better, equal or worse therapeutic effects in comparison with other antidiabetic interventions for patients with T2DM remains controversial. OBJECTIVES: To assess the effects of sulphonylurea monotherapy versus placebo, no intervention or other antidiabetic interventions for patients with T2DM. SEARCH METHODS: We searched publications in The Cochrane Library, MEDLINE, EMBASE, Science Citation Index Expanded, LILACS and CINAHL (all until August 2011) to obtain trials fulfilling the inclusion criteria for our review. SELECTION CRITERIA: We included clinical trials that randomised patients 18 years old or more with T2DM to sulphonylurea monotherapy with a duration of 24 weeks or more. DATA COLLECTION AND ANALYSIS: Two authors independently assessed the risk of bias. The primary outcomes were all-cause and cardiovascular mortality. Secondary outcomes were other patient-important outcomes and metabolic variables. Where possible, we used risk ratios (RR) with 95% confidence intervals (95% CI) to analyse the treatment effect of dichotomous outcomes. We used mean differences with 95% CI to analyse the treatment effect of continuous outcomes. We evaluated the risk of bias. We conducted trial sequential analyses to assess whether firm evidence could be established for a 10% relative risk reduction (RRR) between intervention groups. MAIN RESULTS: We included 72 randomised controlled trials (RCTs) with 22,589 participants; 9707 participants randomised to sulphonylureas versus 12,805 participants randomised to control interventions. The duration of the interventions varied from 24 weeks to 10.7 years. We judged none of the included trials as low risk of bias for all bias domains. Patient-important outcomes were seldom reported.First-generation sulphonylureas (FGS) versus placebo or insulin did not show statistical significance for all-cause mortality (versus placebo: RR 1.46, 95% CI 0.87 to 2.45; P = 0.15; 2 trials; 553 participants; high risk of bias (HRB); versus insulin: RR 1.18, 95% CI 0.88 to 1.59; P = 0.26; 2 trials; 1944 participants; HRB). FGS versus placebo showed statistical significance for cardiovascular mortality in favour of placebo (RR 2.63, 95% CI 1.32 to 5.22; P = 0.006; 2 trials; 553 participants; HRB). FGS versus insulin did not show statistical significance for cardiovascular mortality (RR 1.36, 95% CI 0.68 to 2.71; P = 0.39; 2 trials; 1944 participants; HRB). FGS versus alpha-glucosidase inhibitors showed statistical significance in favour of FGS for adverse events (RR 0.63, 95% CI 0.52 to 0.76; P = 0.01; 2 trials; 246 participants; HRB) and for drop-outs due to adverse events (RR 0.28, 95% CI 0.12 to 0.67; P = 0.004; 2 trials; 246 participants; HRB).Second-generation sulphonylureas (SGS) versus metformin (RR 0.98, 95% CI 0.61 to 1.58; P = 0.68; 6 trials; 3528 participants; HRB), thiazolidinediones (RR 0.92, 95% CI 0.60 to 1.41; P = 0.70; 7 trials; 4955 participants; HRB), insulin (RR 0.96, 95% CI 0.79 to 1.18; P = 0.72; 4 trials; 1642 participants; HRB), meglitinides (RR 1.44, 95% CI 0.47 to 4.42; P = 0.52; 7 trials; 2038 participants; HRB), or incretin-based interventions (RR 1.39, 95% CI 0.52 to 3.68; P = 0.51; 2 trials; 1503 participants; HRB) showed no statistically significant effects regarding all-cause mortality in a random-effects model. SGS versus metformin (RR 1.47; 95% CI 0.54 to 4.01; P = 0.45; 6 trials; 3528 participants; HRB), thiazolidinediones (RR 1.30, 95% CI 0.55 to 3.07; P = 0.55; 7 trials; 4955 participants; HRB), insulin (RR 0.96, 95% CI 0.73 to 1.28; P = 0.80; 4 trials; 1642 participants; HRB) or meglitinide (RR 0.97, 95% CI 0.27 to 3.53; P = 0.97; 7 trials, 2038 participants, HRB) showed no statistically significant effects regarding cardiovascular mortality. Mortality data for the SGS versus placebo were sparse. SGS versus thiazolidinediones and meglitinides did not show statistically significant differences for a composite of non-fatal macrovascular outcomes. SGS versus metformin showed statistical significance in favour of SGS for a composite of non-fatal macrovascular outcomes (RR 0.67, 95% CI 0.48 to 0.93; P = 0.02; 3018 participants; 3 trials; HRB). The definition of non-fatal macrovascular outcomes varied among the trials. SGS versus metformin, thiazolidinediones and meglitinides showed no statistical significance for non-fatal myocardial infarction. No meta-analyses could be performed for microvascular outcomes. SGS versus placebo, metformin, thiazolidinediones, alpha-glucosidase inhibitors or meglitinides showed no statistical significance for adverse events. SGS versus alpha-glucosidase inhibitors showed statistical significance in favour of SGS for drop-outs due to adverse events (RR 0.48, 95% CI 0.24 to 0.96; P = 0.04; 9 trials; 870 participants; HRB). SGS versus meglitinides showed no statistical significance for the risk of severe hypoglycaemia. SGS versus metformin and thiazolidinediones showed statistical significance in favour of metformin (RR 5.64, 95% CI 1.22 to 26.00; P = 0.03; 4 trials; 3637 participants; HRB) and thiazolidinediones (RR 6.11, 95% CI 1.57 to 23.79; P = 0.009; 6 trials; 5660 participants; HRB) for severe hypoglycaemia.Third-generation sulphonylureas (TGS) could not be included in any meta-analysis of all-cause mortality, cardiovascular mortality or non-fatal macro- or microvascular outcomes. TGS versus thiazolidinediones showed statistical significance regarding adverse events in favour of TGS (RR 0.88, 95% CI 0.78 to 0.99; P = 0.03; 3 trials; 510 participants; HRB). TGS versus thiazolidinediones did not show any statistical significance for drop-outs due to adverse events. TGS versus other comparators could not be performed due to lack of data.For the comparison of SGS versus FGS no meta-analyses of all-cause mortality, cardiovascular mortality, non-fatal macro- or microvascular outcomes, or adverse events could be performed.Health-related quality of life and costs of intervention could not be meta-analysed due to lack of data.In trial sequential analysis, none of the analyses of mortality outcomes, vascular outcomes or severe hypoglycaemia met the criteria for firm evidence of a RRR of 10% between interventions. AUTHORS' CONCLUSIONS: There is insufficient evidence from RCTs to support the decision as to whether to initiate sulphonylurea monotherapy. Data on patient-important outcomes are lacking. Therefore, large-scale and long-term randomised clinical trials with low risk of bias, focusing on patient-important outcomes are required.

Breech delivery in low-income settings: A systematic review of perinatal and maternal outcomes in vaginal versus cesarean breech deliveries.

Most studies comparing vaginal breech delivery (VBD) with cesarean breech delivery (CBD) have been conducted in high-income settings. It is uncertain whether these results are applicable in a low-income setting. To assess the neonatal and maternal mortality and morbidity for singleton VBD compared to CBD in low- and lower-middle-income settings,the PubMed database was searched from January 1, 2000, to January 23, 2020 (updated April 21, 2021). Randomized controlled trials (RCTs) and non-RCTs comparing singleton VBD with singleton CBD in low- and lower-middle-income settings reporting infant mortality were selected. Two authors independently assessed papers for eligibility and risk of bias. The primary outcome was relative risk of perinatal mortality. Meta-analysis was conducted on applicable outcomes. Eight studies (one RCT, seven observational) (12 510 deliveries) were included. VBD increased perinatal mortality (relative risk [RR] 2.67, 95% confidence interval [CI] 1.82-3.91; one RCT, five observational studies, 3289 women) and risk of 5-minute Apgar score below 7 (RR 3.91, 95% CI 1.90-8.04; three observational studies, 430 women) compared to CBD. There was a higher risk of hospitalization and postpartum bleeding in CBD. Most of the studies were deemed to have moderate or serious risk of bias. CBD decreases risk of perinatal mortality but increases risk of bleeding and hospitalization.

Dealing with substantial heterogeneity in Cochrane reviews. Cross-sectional study.

BACKGROUND: Dealing with heterogeneity in meta-analyses is often tricky, and there is only limited advice for authors on what to do. We investigated how authors addressed different degrees of heterogeneity, in particular whether they used a fixed effect model, which assumes that all the included studies are estimating the same true effect, or a random effects model where this is not assumed. METHODS: We sampled randomly 60 Cochrane reviews from 2008, which presented a result in its first meta-analysis with substantial heterogeneity (I2 greater than 50%, i.e. more than 50% of the variation is due to heterogeneity rather than chance). We extracted information on choice of statistical model, how the authors had handled the heterogeneity, and assessed the methodological quality of the reviews in relation to this. RESULTS: The distribution of heterogeneity was rather uniform in the whole I2 interval, 50-100%. A fixed effect model was used in 33 reviews (55%), but there was no correlation between I2 and choice of model (P = 0.79). We considered that 20 reviews (33%), 16 of which had used a fixed effect model, had major problems. The most common problems were: use of a fixed effect model and lack of rationale for choice of that model, lack of comment on even severe heterogeneity and of reservations and explanations of its likely causes. The problematic reviews had significantly fewer included trials than other reviews (4.3 vs. 8.0, P = 0.024). The problems became less pronounced with time, as those reviews that were most recently updated more often used a random effects model. CONCLUSION: One-third of Cochrane reviews with substantial heterogeneity had major problems in relation to their handling of heterogeneity. More attention is needed to this issue, as the problems we identified can be essential for the conclusions of the reviews.

Industry sponsorship and research outcome: systematic review with meta-analysis.

PURPOSE: Clinical research is widely sponsored by drug and device companies. We investigated whether industry sponsored drug and device studies have more favorable outcomes and differ in risk of bias, compared with studies having other sources of sponsorship. This review is an update of a previous Cochrane review. METHODS: In this update we searched MEDLINE and Embase (2010 to February 2015), Cochrane Methodology Register (2015, Issue 2) and Web of Science (June 2015). We included empirical studies that quantitatively compared primary research studies of drugs or medical devices sponsored by industry with studies with other sources of sponsorship. Two assessors included papers, extracted data and assessed risk of bias. Outcomes included favorable results, favorable conclusions, effect size, risk of bias and whether conclusions agreed with results. RESULTS: We included 27 additional papers in this update (review now includes 75 papers). Industry sponsored studies more often had favorable efficacy results, RR: 1.27 (95% CI 1.17-1.37), no difference in harms results RR: 1.37 (95% CI 0.64-2.93) and more often favorable conclusions RR: 1.34 (95% CI 1.19-1.51) compared with non-industry sponsored studies. Nineteen papers reported on sponsorship and efficacy effect size, but could not be pooled due to differences in reporting of data and heterogeneity of results. Comparing industry and non-industry sponsored studies, we did not find a difference in risk of bias from sequence generation, allocation concealment, follow-up and selective outcome reporting. However, industry sponsored studies more often had low risk of bias from blinding, RR: 1.25 (95% CI 1.05-1.50), compared with non-industry sponsored studies. CONCLUSIONS: Drug and device studies sponsored by manufacturing companies have more favorable efficacy results and conclusions than studies sponsored by other sources.

Sulfonylurea versus metformin monotherapy in patients with type 2 diabetes: a Cochrane systematic review and meta-analysis of randomized clinical trials and trial sequential analysis.

BACKGROUND: Guidelines recommend metformin as the first-line oral treatment for type 2 diabetes. We conducted a systematic review to assess whether the use of second- and third-generation sulfonylurea agents is associated with benefits and harms in terms of patient-important outcomes compared with metformin. METHODS: We searched several electronic databases and other sources for randomized clinical trials published to August 2011. We included trials that compared sulfonylurea versus metformin monotherapy among patients 18 years or older with type 2 diabetes and that had an intervention period of at least 24 weeks. We assessed risk of bias and extracted data related to interventions and outcomes. The risk of random errors was assessed by trial sequential analysis. RESULTS: We included 14 trials (4560 participants). All trials were judged to be at high risk of bias. Data on patient-important outcomes were sparse. Compared with metformin, sulfonylurea did not significantly affect all-cause mortality (relative risk [RR] 0.98, 95% confidence interval [CI] 0.61 to 1.58) or cardiovascular mortality (RR 1.47, 95% CI 0.54 to 4.01). Sulfonylurea significantly decreased the risk of nonfatal macrovascular outcomes (RR 0.67, 95% CI 0.48 to 0.93). However, the definition of this outcome varied among trials, and trial sequential analysis showed that more trials are needed before reliable conclusions can be drawn. No differences between sulfonylurea and metformin were found for change in fasting blood glucose level or glycosylated hemoglobin concentration in the random-effects model. Sulfonylurea resulted in greater weight gain compared with metformin, a finding confirmed in the trial sequential analysis. Significantly more patients in the sulfonylurea arm than in the metformin arm had mild hypoglycemia (RR 2.95, 95% CI 2.13 to 4.07) and severe hypoglycemia (RR 5.64, 95% CI 1.22 to 26.00). INTERPRETATION: Some evidence suggests that, compared with metformin, second- and third-generation sulfonylureas may not affect all-cause or cardiovascular mortality but may decrease the risk of nonfatal macrovascular outcomes among patients with type 2 diabetes. They may also increase the risk of hypoglycemia. In general, the available data were too few and inconsistent to provide firm evidence concerning patient-important outcomes in relation to the benefits and harms of sulfonylurea versus metformin monotherapy.