CONCLUSIONS Antihypertensive treatment reduces the risk of mortality and cardiovascular morbidity in people with diabetes mellitus and a systolic blood pressure more than 140 mm Hg .
If systolic blood pressure is less than 140 mm Hg , however , further treatment is associated with an increased risk of cardiovascular death , with no observed benefit
OBJECTIVE To assess the effect of antihypertensive treatment on mortality and cardiovascular morbidity in people with diabetes mellitus , at different blood pressure levels .
The Medical Review Article Revisited: Has the Science Improved?
Review articles are an important element of most medical journals and a popular source of information for clinicians ( 1 ) . Given the increasing volume of medical literature and the limited time for reading that busy clinicians have , reliance on review articles is likely to increase . However , concerns have been raised that narrative , non systematic review articles may produce biased conclusions ( 2 , 3 ) . Mulrow ( 4 ) examined 50 review articles published in four major medical journals ( The New Engl and Journal of Medicine , Annals of Internal Medicine , JAMA , and Archives of Internal Medicine ) in 1985 - 1986 and found that none fulfilled 8 explicit criteria for scientifically sound summaries of the evidence . As a result , she and others ( 5 , 6 ) proposed criteria for conducting and evaluating review articles that would improve their quality ; these criteria are the first 10 listed in the Appendix Table . In a study of 36 review articles done by nine content experts and method ologists , these criteria were shown to yield reliable and valid estimates of the scientific quality of review s ( 7 , 8) . We sought to describe the methods used in recently published review articles and determine whether the attention paid to the method ologic shortcomings of review articles has led to improvements in their scientific quality . Methods By using the Science Citation Index ( 9 ) , we stratified the 12 general medicine journals that are considered core journals for ACP Journal Club ( 10 ) into those with high impact factors ( scores 5 ) and those with lower impact factors . We r and omly selected 3 ( The New Engl and Journal of Medicine , Annals of Internal Medicine , and JAMA ) of the 4 high-impact core journals and 3 ( British Medical Journal , American Journal of Medicine , and Journal of Internal Medicine ) of the 8 core journals with lower impact factors . The sampling frame included 3 of the 4 journals examined in Mulrow 's original study ( 4 ) . All 6 journals were h and - search ed by two of the investigators independently , and review articles published between January and December 1996 were retrieved . Review articles were defined as full-text articles published under the banner review that dealt with disease states ; had the words review , overview , or meta- analysis in the title or abstract ; or indicated in the text that the intention was to review or summarize the literature about a clinical topic . Editorials , correspondence , and conference summaries were excluded . Disagreements on article eligibility ( which occurred in five cases ) were resolved by consensus . After training with a test set of articles , five of the authors used explicit criteria ( Appendix Table ) to rate the identified review articles . So that the raters ' assessment s would be blinded , the articles ' authors , author affiliations , and sources of articles were masked . The first 10 criteria in the Appendix Table ( hereafter referred to as method ologic criteria ) have been previously vali date d ( 7 ) and assess method ologic rigor , whereas the last five criteria were developed for this study to evaluate the scientific basis of treatment recommendations . Because inter-rater agreement was excellent on the test set ( overall agreement , 94 % ) , each rater was assigned a r and om sample of 20 % of the articles . One rater independently evaluated a r and om sample of five articles from each rater to assess inter-rater reliability for the criteria . The mean value was 0.79 , indicating substantial agreement ; overall agreement was 95 % and ranged from 84 % for criteria 1 and 6 to 100 % for criteria 2 , 3 , and 5 . After we determined the number of criteria fulfilled by each article , the number of articles meeting each criterion was ascertained . The proportion of review s from high-impact journals and from lower-impact journals that met each criterion were compared . Only the subset of review s containing treatment recommendations were used for the comparisons for criteria 7 to 15 . The chi-square test was used and 95 % CIs for the observed differences were calculated for all comparisons . In addition , articles identified as meta-analyses , systematic review s , or overviews in their title , abstract , or text were compared with the remaining review articles for each criterion ( again by using the chi-square test and by limiting analysis to those that included treatment recommendations for criteria 7 to 15 ) . Logistic regression analysis was used to adjust for journal of publication . The funding organizations were not involved in the design , conduct , analysis , or reporting of this study . Results A total of 158 review articles were identified : 60 from The New Engl and Journal of Medicine , 33 from Annals of Internal Medicine , 24 from British Medical Journal , 18 from American Journal of Medicine , 13 from JAMA , and 10 from Journal of Internal Medicine . ( A full list of the included articles is available from Dr. McAlister on request . ) Most review s were written by more than one author ( median number of authors , 2 [ range , 1 to 10 authors ] ) , and 111 review s ( 70 % ) made treatment recommendations . Although most articles had sections review ing the relevant pathophysiology and pharmacodynamics , 19 articles ( 12 % ) were largely basic science review s. Only 2 review s met all 10 method ologic criteria ; the median number of criteria fulfilled was one ( Figure ) . Nineteen ( 12 % ) of the review articles were described as meta- analysis , systematic review , or overview in the title or abstract ; 12 of these 19 articles were published in high-impact journals . A higher proportion of these articles met the method ologic criteria ( Appendix Table ) ; the comparisons for all but criterion 6 were statistically significant , even after adjustment for journal of publication ( P<0.005 for all comparisons ) . Although there was significant heterogeneity among journals ( P<0.005 for criteria 1 to 5 , 7 , and 8) , review articles published in high-impact journals did not meet method ologic criteria more frequently than those published in other journals ( Table ) . Exclusion of the review s from one journal with method ologic scores that were significantly lower than the rest ( P<0.001 for all comparisons ) resolved much of the interjournal heterogeneity and revealed that review s published in the remaining high-impact journals more often met some ( but not all ) of the method ologic criteria ( Table ) . Figure . Percentage of 158 review articles published in 1996 that fulfilled specific method ologic criteria . Table . Comparison of Methods Used in 1996 Review Articles , by Journal Impact Factor The 44 articles that described how evidence was located used the following sources ( which were not mutually exclusive ) : MEDLINE ( 42 articles ) , h and search of reference lists from published studies or review articles ( 30 articles ) , other electronic data bases ( 14 articles ) , contact with experts in the field ( 10 articles ) , h and search of relevant journals ( 7 articles ) , and contact with the pharmaceutical industry ( 5 articles ) . Of the 22 review s that included a description of the electronic search strategy , the search was restricted to English- language publications in 11 . Of the 111 review s in which treatment recommendations were made , a median of 3 therapies ( range , 1 to 23 therapies ) were discussed . The 16 meta-analyses that included treatment recommendations were more focused , examining a median of 1 therapy ( range , 1 to 6 therapies ) . The scientific basis of these recommendations is outlined in the last five criteria of the Appendix Table . Discussion In summary , only a minority of the review articles published in six widely read general medical journals specified rigorous , systematic methods of identifying , evaluating , and synthesizing the evidence , thereby raising concerns about the validity of their conclusions and recommendations ( 11 ) . Furthermore , although most review articles made recommendations for therapeutic options , their clinical relevance may be limited : Only one third discussed benefits and harms of the treatment options , only 6 % mentioned the relative or absolute costs of the various options , less than half provided an estimate of the anticipated treatment effect , and very few presented the results in clinical ly relevant formats that would be easily understood by clinicians . Although there is still substantial room for improvement , these results do represent progress from the situation in 1985 - 1986 ( Appendix Table ) . A higher proportion of recently published review s specify how the evidence was identified and synthesized . This same pattern was observed in a recent study of oncology review articles published in a single journal between 1983 and 1995 ( 12 ) . Similarly , our findings for meta-analyses published in these journals in 1996 are consistent with contemporaneous investigations in other fields and represent substantial improvement over the state of affairs in the mid-1980s ( 13 , 14 ) . Our study had several potential limitations . First , the authors of articles in which systematic methods were not specified may have used such methods but not reported them ( or the journal may have removed the details of the methods in prepublication ) . However , preliminary evidence suggests that there is little difference between the conduct of studies and their published methods ( 7 , 15 ) . In other words , if what was done is not reported , there is a good chance that it was not done rigorously ( 7 ) . Second , our finding that meta-analyses are more scientifically rigorous than other review s may be seen as tautological because the criteria used in this study may be used by meta-analysts in performing their studies . However , meta-analysts disagree over some issues of methodology , and published meta-analyses often vary in the quality of their reports ( 13 ) . Third , the practical importance of the method ologic flaws identified in these review s is difficult to ascertain . We lack empirical evidence that review s with explicit , systematic methods yield results closer to the truth , but it is known that non systematic review s are more prone to r and om and
CONCLUSIONS Antihypertensive treatment reduces the risk of mortality and cardiovascular morbidity in people with diabetes mellitus and a systolic blood pressure more than 140 mm Hg .
If systolic blood pressure is less than 140 mm Hg , however , further treatment is associated with an increased risk of cardiovascular death , with no observed benefit
OBJECTIVE To assess the effect of antihypertensive treatment on mortality and cardiovascular morbidity in people with diabetes mellitus , at different blood pressure levels .