title: How Quickly Do Systematic Reviews Go Out of Date? A Survival Analysis Caries-preventive effect of glass ionomer and resin-based fissure sealants on permanent teeth: An update of systematic review evidence Caries-preventive effect of sealants produced with altered glass-ionomer materials, after 2 years. The success rates of a glass ionomer cement and a resin-based fissure sealant placed by fifth-year undergraduate dental students Caries-preventive efficacy and retention of a resin-modified glass ionomer cement and a resin-based fissure sealant: a 3-year split-mouth randomised clinical trial.
abstract: Context Clinicians rely on systematic review s for current , evidence -based information . Contribution This survival analysis of 100 meta-analyses indexed in ACP Journal Club from 1995 to 2005 found that new evidence that substantively changed conclusions about the effectiveness or harms of therapies arose frequently and within relatively short time periods . The median survival time without substantive new evidence for the meta-analyses was 5.5 years . Significant new evidence was already available for 7 % of the review s at the time of publication and became available for 23 % within 2 years . Implication Clinical ly important evidence that alters conclusions about the effectiveness and harms of treatments can accumulate rapidly . The Editors Systematic review s have become increasingly common in recent years ( 1 ) and are recommended by many as the best sources of evidence to guide both clinical decisions ( 2 ) and health care policy ( 3 ) . For systematic review s to fulfill these roles , their findings must remain relatively stable for at least several years or effective mechanisms must exist for alerting end users to important changes in evidence . Yet , surprisingly little research has assessed the extent to which systematic review s become out of date or the rate at which this occurs ( 47 ) . Some organizations , such as the Cochrane Collaboration , recommend updating systematic review s every 2 years , but few empirical data guide this or other recommendations about updating . We sought to determine how quickly systematic review s meet explicitly defined criteria for changes in evidence of sufficient importance to warrant updating . We also sought to identify predictors of survival time , the time to such important changes in evidence . Survival time might vary depending on many factors , including the type of question posed by the original review ( for example , therapeutic or diagnostic ) , the types of studies included ( for example , r and omized trials or observational studies ) , and whether the systematic review provided quantitative synthesis . To limit such variation , we focused on systematic review s of r and omized , controlled trials that evaluated therapeutic benefit or harm by providing quantitative synthesis ( meta- analysis ) for at least 1 outcome . Methods Study Design and Sample We used a quasi-r and om process ( alphabetical sort order by author ) to select 100 systematic review s that were indexed in ACP Journal Club with an accompanying commentary between January 1995 and December 2005 ( with a search date no later than 31 December 2004 to ensure at least 1 full year for new evidence to appear ) . We chose this sampling frame because ACP Journal Club selects systematic review s that meet explicit quality st and ards and are deemed directly relevant to clinical practice ( 8) . We regarded the sample size of 100 as sufficiently large to achieve suitably narrow confidence intervals and to permit evaluation of up to 5 potential predictors of survival . Eligibility Criteria Eligible review s evaluated the benefit or harm of a specific drug , class of drug , device , or procedure ( invasive procedure or surgery ) and included r and omized or quasi-r and omized , controlled trials . We excluded evaluations of alternative and complementary medicines because the stability of review s of such therapies might differ substantially from review s of conventional therapies . We required that review s provide a point estimate and 95 % confidence interval for at least 1 outcome in the form of a relative risk , odds ratio , or absolute risk difference for binary outcomes and weighted mean differences for continuous outcomes . We excluded meta-analyses of individual-patient data , meta-regressions , and indirect meta-analyses because of the difficulty of determining whether new data would alter previous quantitative results . Two team members independently assessed eligibility , with disagreements resolved by consensus involving a third review er . When more than 1 review on the same topic was identified , only the earliest was included . Search ing For each review , search es for new trials included identifying new systematic review s on the same topic , su bmi tting relevant content terms to the Clinical Queries function in Ovid , applying the Related Articles function in PubMed to the 3 largest and the 3 most recent trials in the original review ( up to 6 trials in total ) , and using Scopus ( www . scopus .com/ scopus /home.url ) to identify new r and omized trials that cited the original review . When these search strategies yielded no eligible new trials , we conducted more comprehensive electronic search es and review ed relevant chapters in such sources as Clinical Evidence and UpTo Date to ensure that we had not missed new trials . Team members who had background s in both medicine and clinical research screened citations retrieved by the preceding methods to identify trials that would have met the inclusion criteria in the original review . Retrieved articles were screened in chronological order to ascertain quantitative or qualitative signals for the need for updating . The review protocol stopped when any criteria for updating were met . Each systematic review was discussed in detail , with the final statussignal for updating was or was not detectedadjudicated by consensus ( Figure 1 ) . Figure 1 . Overall process for determining updating status . ACP Journal Club Signals for the Need to Up date Systematic Review s In design ing criteria for comparing new findings with those in a previous review , we adapted methods used by other investigators to address similar problems with comparing 2 sets of results relating to the same question ( 913 ) , such as r and omized and nonr and omized studies of the same intervention . These investigators identified conflicting findings among different publications using a combination of quantitative thresholds for differences in effect magnitude and qualitative judgments about the language used to describe the results . We have similarly conceptualized quantitative and qualitative signals of potential changes in evidence that are sufficiently important to warrant updating previous systematic review s. Quantitative Signals Quantitative signals consisted of a change in statistical significance or relative change in effect magnitude of at least 50 % . We restricted these changes to those involving 1 of the primary outcomes of the original review or any mortality outcome . We also ignored trivial changes in statistical significance when the original and up date d meta-analytic results both had P values between 0.04 and 0.06so that quantitative signals of changes in evidence would represent robust indicators of the need to up date previous review s. Quantitative signals were detected by combining data from eligible new trials with the previous results using a fixed-effects approach . Use of fixed-effect models allowed pooling of the new trials with the previous meta-analytic result , as opposed to having to obtain original data from all of the included trials in each of 100 systematic review s. Although r and om-effects models are usually preferred to avoid spurious precision in the face of heterogeneity , our goal was to detect potential changes in evidence that would warrant a formal up date , not produce exact estimates of the up date d results . Qualitative Signals Qualitative signals included new information about harm sufficient to affect clinical decision making , important caveats to the original results , emergence of a superior alternate therapy , and important changes in certainty or direction of effect . Qualitative signals were detected by using explicit criteria for comparing the language in the original review with descriptions of findings in new systematic review s that addressed the same topic , pivotal trials , clinical practice guidelines , or recent editions of major textbooks ( for example , UpTo Date ) . Pivotal trials were defined as trials that had a sample size at least 3 times larger than that of the previous largest trial or were published in 1 of the 5 highest-impact general medical journals ( The New Engl and Journal of Medicine , Lancet , Journal of the American Medical Association , Annals of Internal Medicine , and the British Medical Journal ) . We defined 2 levels of importance for qualitative signals : potentially invalidating changes in evidence , which would make one no longer want clinicians or policymakers to base decisions on the original findings ( such as a pivotal trial that characterized treatment effectiveness in terms opposite of those in the original systematic review ) , and major changes in evidence , which would affect clinical decision making in important ways without invalidating the previous results ( such as the identification of patient population s for whom treatment is more or less beneficial ) . Major changes also included differing characterizations of effectiveness that were less extreme than those for potentially invalidating signals but that would still affect clinical decision making ( for example , a change from possibly beneficial to definitely beneficial ) . Of importance , such characterizations as possibly effective , probably effective , and promising , were all categorized as possibly effective . Thus , qualitative signals for changes in evidence captured substantive differences in the characterization of treatment effects , not merely semantic differences . Full definitions for each of the specific signals can be found at www.ohri.ca/UpdatingSystRevs . Data Collection For each review , we characterized the clinical content area , eligibility criteria for included trials , definitions of reported outcomes , number of included trials and participants , meta-analytic result for each outcome , identification of statistical heterogeneity , and excerpted quotations of the authors ' characterizations of the main results . We also abstract ed whether a given outcome was explicitly identified as 1 of the primary or main outcomes . We discounted identification of more than 3 such outcomes as inconsistent with the Background This article constitutes a partial up date of the original systematic review evidence by Yengopal et al. from 15 January 2008 ( published in the Journal of Oral Science in 2009 ) with primary focus on research quality in regard to bias risk in trials . Its aim is to up date the existing systematic review evidence from the English literature as to whether caries occurrence on pits and fissures of teeth sealed with either GIC or resin is the same . Methods In addition to the 12 trials included during the original systematic review , 5 new trials were identified during the data base search ( up to 26 August 2010 ) and 2 further trials were included from a h and search and reference check . Of these , 3 trials were excluded and 16 were accepted for data extraction and quality assessment . The quality of accepted trials was assessed , using up date d quality criteria , and the risk of bias was investigated in more depth than previously reported . In addition , the focus of quantitative synthesis was shifted to single data sets that were extracted from the accepted trials . Results Twenty-six dichotomous and 4 continuous data sets were extracted . Meta- analysis and cumulative meta- analysis were used in combining clinical ly homogenous data sets . The overall outcome of the computed data sets suggest no difference between the caries-preventive effects of GIC- and resin-based fissure sealants . Conclusions This overall outcome is in agreement with the conclusions of the original systematic review . Although the findings of the trials identified in this up date may be considered to be less affected by attrition- and publication bias , their risk of selection - and detection-/performance bias is high . Thus , verification of the currently available results requires further high quality r and omised control trials OBJECTIVES The aim of the present study was to investigate the caries-preventive effect of sealants produced with a high-viscosity glass-ionomer with an elevated powder-liquid ratio ( ART ) , of having energy added to this glass-ionomer , and that of glass-carbomer , in comparison to that of resin composite sealants . METHODS The r and omized controlled trial covered 407 children , with a mean age of 8 years . At a school compound three dentists placed sealants in pits and fissures of high caries-risk children . Evaluation by two independent evaluators was conducted after 0.5 , 1 and 2 years . The Kaplan-Meier survival method , ANOVA and t-test were used in analyzing the data . RESULTS 1352 first permanent molars were sealed . 6.6 % of children and 6.8 % of sealants dropped out within 2 years . 27 re-exposed pits and fissures , 20 in occlusal and 7 in smooth surfaces , in 25 children , developed a dentin carious lesion . The cumulative survival of dentin carious lesion-free pits and fissures in the  glass-carbomer sealant group was statistically significantly lower ( 97.4 % ) than those in the high-viscosity glass-ionomer with energy supplied ( 99 % ) and the resin-composite ( 98.9 % ) sealant groups . There was no statistically significant difference in the cumulative survival of dentin carious lesion-free pits and fissures , between the high-viscosity glass-ionomer with ( 99 % ) and without ( 98.3 % ) energy supplied sealant groups , after 2 years . SIGNIFICANCE The survival of dentin carious lesion-free pits and fissures was high in all sealant types . More dentin carious lesions were observed in the glass-carbomer sealant group AIM : To evaluate retention and caries prevention of a glass-ionomer cement ( GIC ) and a resin-based fissure sealant placed by fifth-year undergraduate dental students . METHODS : The study was conducted according to a split-mouth , r and omised clinical trial . Children with at least one pair of caries-free permanent first molars with deep pits and fissures were included in the study . The children were selected from a population that had a high risk for dental caries .  Sealant material s were applied by fifth-year undergraduate dental students on 346  fissures of the first permanent molars in 173 children . The ages of the children ranged from 7–15 years ( mean 9.4 ) . Two research ers at the clinics supervised all of the procedures . Intra-examiner reproducibility and inter-examiner reproducibility were 0.90 and 0.86 , respectively , for the clinical assessment of sealant retention and caries evaluation . RESULTS :  GIC sealants were completely lost in 31.9 % and resin-based sealants in 16.6 % ( p<0.05 ) . The total retention rates of GIC sealants and resin-based sealants were 13.8 % and 20.8 % , respectively . After 24 months , the caries increment was 3.4 % for GIC sealants and 4.8 % for resin-based sealants ( p>0.05 ) . CONCLUSIONS : The retention of GIC sealants was markedly inferior to the retention of resin-based sealants ; however , GIC when used as a pit and fissure sealant was slightly more effective in preventing occlusal caries PURPOSE This prospect i ve clinical trial compared the retention rate and caries-preventive efficacy of two types of sealant modalities over a 3-year period . MATERIAL S AND METHODS Using a split-mouth r and omised design , 1280 sealants were r and omly applied on sound permanent second molars of 320 young patients aged between 12 and 16 years . Half of the teeth ( n = 640 ) were sealed with a resin-modified glass ionomer cement ( RMGIC ) ( Vitremer ™ , 3 M ESPE ) and the other half ( n = 640 ) with a conventional light-cure , resin-based fissure sealant ( LCRB ) ( Fluoroshield ® , Dentsply Caulk ) . Teeth were evaluated at baseline , 6- , 12- , 18- , 24- , 30- and 36-month intervals with regard to retention and new caries development . RESULTS On the sealed occlusal surfaces after 3 years , 5.10 % of RMGIC and 91.08 % of LCRB sealants were totally intact and 6.37 % of RMGIC and 7.65 % of LCRB sealants were partially intact . New caries lesions were found in 20.06 % of RMGIC sealed occlusal surfaces , compared to 8.91 % for LCRB sealants . CONCLUSIONS The findings of the present clinical study suggest that RMGIC should be used only as a transitional sealant that can be applied to newly erupting teeth throughout the eruptive process , whereas LCRB sealants are used to successfully prevent occlusal caries lesions once an effective rubber dam can be achieved . It can be concluded that there are differences between the RMGIC and LCRB sealants over a 3-year period in terms of the retention rate and caries-preventive efficacy . RMGIC can serve as a simple and economic sealing solution , however provisional . Due to its poor retention rate , periodic recalls are necessary , even after 6 months , to eventually replace the lost sealant
target: The content of these signals suggest that higher precision of the current systematic review results might be achieved if an up date of the current review were conducted at this point in time .
  However , these signals further indicate that such systematic review up date , despite its higher precision , would only confirm the existing review conclusion that no statistically significant difference exists in the caries-preventive effect of GIC and resin-based fissure sealants .
  In conclusion , this study demonstrated the modified Ottawa method as an effective tool in establishing the up date need of the systematic review .
background: OBJECTIVE To demonstrate the application of the modified Ottawa method by establishing the up date need of a systematic review with focus on the caries preventive effect of GIC versus resin pit and fissure sealants ;  to answer the question as to whether the existing conclusions of this systematic review are still current ; to establish whether a new up date of this systematic review was needed .