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 .
Systematic Reviews: Synthesis of Best Evidence for Clinical Decisions
At the end of a long week in the office , you sink back into your chair , reflecting on some of the more memorable patients you cared for and counseled . Through gentle history taking , you discovered that urinary incontinence is the underlying cause of an elderly patient 's increasing social isolation . During a careful physical examination , you detected bruising on the torso of a woman with chronic headaches and began to explore the longst and ing abusive relationship between the woman and her alcoholic partner . You discontinued procainamide therapy in a 72-year-old man who had asymptomatic premature ventricular contractions after myocardial infa rct ion . To prevent bleeding from esophageal varices , you started -blocker therapy in a woman with long-st and ing cryptogenic cirrhosis and portal hypertension . In couples ' therapy , discussing the future quality of life of a middle-aged gay man with human immunodeficiency virus infection , you journeyed through emotionally intense dialogue about advance directives . You presented the risk factors for major and minor bleeding to a 39-year-old woman who was considering warfarin therapy because of recently diagnosed atrial fibrillation and valvular heart disease . You listened to , made diagnoses for , treated , advised , and comforted many patients . Yet there were some hiccoughs in your practice along the way . You stumbled while debating the pros and cons of breast cancer screening with a healthy 48-year-old woman who has been staying current with information on the Internet . You question ed the merits of a personalized walking program suggested to you by a motivated 66-year-old man with severe claudication . Explaining that you wanted to review the best current evidence on these issues , you resolved to address your uncertainties before these patients made their next office visits , in a week 's time . Sighing deeply , you acknowledge that you have little time to read . You subscribe to three journals , which you browse months after they arrive-either when your journal stack becomes precariously high or when your guilt is sufficiently motivational . You sometimes find the conclusions of individual articles conflicting or confusing . You know that some of the decisions and suggestions you made this week , specifically your decisions about stopping procainamide therapy and starting -blocker therapy and your advice about bleeding risks from anticoagulant therapy , were based on the best current research evidence [ 1 - 3 ] . On the other h and , your patients ' inquiries about breast cancer screening and exercise treatment for claudication highlight your need for a concise , current , rigorous synthesis of the best available evidence on each of these topics : in brief , a systematic review [ 4 , 5 ] . Incorporating Research Evidence into Clinical Decision Making The foregoing scenario is familiar to practitioners . In a typical week , we encounter patients with diverse problems ; exercise numerous clinical , interpersonal , and technical skills ; and make many decisions . The factors that affect these decisions and their outcomes are complex . For instance , each patient has unique sociodemographic characteristics , cultural circumstances , and personal preferences . Each physician has unique knowledge , experiences , and values . Moreover , practitioners and their patients make decisions within the context of a rapidly changing health care system that influences the availability , accessibility , and cost of diagnostic tests and therapies [ 6 ] . Timely , useful evidence from the biomedical literature should be an integral component of clinical decision making . If one treatment has been shown to be better than another , we need to know , so that we can recommend the treatment to the appropriate patients . The worldwide effort to develop new tests and treatments , and to determine their usefulness , has never been stronger , and our patients and their families expect us to be fonts of the knowledge that results from this effort [ 7 ] . Unfortunately , it is easy for current best research evidence to pass us by [ 8 ] . We may lack the time , motivation , and basic skills needed to find , critically appraise , and synthesize information , all of which we must do if we are to integrate the results of original studies into our practice . Fortunately , several potent methods are emerging that can greatly enhance our ability to interpret and apply research evidence ; foremost among them is the systematic review . This article begins a series in Annals that will examine systematic review s in detail and explore their many applications . Systematic review s represent the best chance that most practitioners will have to underst and and accurately apply the key signals arising from the robust and increasingly productive search for solutions to medical problems . A properly conducted systematic review faithfully summarizes the evidence from all relevant studies on the topic of interest , and it does so concisely and transparently . What Is a Systematic Review ? Systematic review s are scientific investigations in themselves , with pre-planned methods and an assembly of original studies as their subjects . They synthesize the results of multiple primary investigations by using strategies that limit bias and r and om error [ 9 , 10 ] . These strategies include a comprehensive search of all potentially relevant articles and the use of explicit , reproducible criteria in the selection of articles for review . Primary research design s and study characteristics are appraised , data are synthesized , and results are interpreted . When the results of primary studies are summarized but not statistically combined , the review may be called a qualitative systematic review . A quantitative systematic review , or meta- analysis , is a systematic review that uses statistical methods to combine the results of two or more studies . The term overview is sometimes used to denote a systematic review , whether quantitative or qualitative . Summaries of research that lack explicit descriptions of systematic methods are often called narrative review s. Review articles are one type of integrative publication ; practice guidelines , economic evaluations , and clinical decision analyses are others . These other types of integrative articles often incorporate the results of systematic review s. For example , practice guidelines are systematic ally developed statements intended to assist practitioners and patients with decisions about appropriate health care for specific clinical circumstances [ 11 ] . Evidence -based practice guidelines are based on systematic review s of the literature , appropriately adapted to local circumstances and values . Economic evaluations compare both the costs and the consequences of different courses of action ; the knowledge of consequences that are considered in these evaluations is often generated by systematic review s of primary studies . Decision analyses quantify both the likelihood and the valuation of the expected outcomes associated with competing alternatives . Differences between Systematic and Narrative Review s All review s , narrative and systematic alike , are retrospective , observational research studies and are therefore subject to systematic and r and om error . Accordingly , the quality of a review - and thus its worth-depends on the extent to which scientific review methods have been used to minimize error and bias . This is the key feature that distinguishes traditional narrative review s from systematic review s ( Table 1 ) . If a review is prepared according to the steps outlined in the right column of Table 1 , it is more likely to be systematic and to provide unbiased conclusions . If review methods approximate those found in the middle column of Table 1 , the article is more likely to be a narrative review , and the conclusions are less likely to be based on an unbiased summary of all relevant evidence . Table 1 . Differences between Narrative Review s and Systematic Review s Systematic review s are generated to answer specific , often narrow , clinical questions in depth . These questions can be formulated explicitly according to four variables : a specific population and setting ( such as elderly out patients ) , the condition of interest ( for example , hypertension ) , an exposure to a test or treatment ( such as pharmacologic management ) , and one or more specific outcomes ( such as cardiovascular and cerebrovascular events and mortality ) [ 12 ] . Thus , an example of a well-formulated , clinical ly relevant question is , Does pharmacologic treatment of hypertension in the elderly prevent strokes and myocardial infa rct ions or delay death ? If the question that is driving the review is not clear from the title , abstract , or introduction , or if no methods section is included , the paper is more likely to be a narrative review than a systematic review [ 13 ] . Most narrative review articles deal with a broad range of issues related to a given topic rather than addressing a particular issue in depth [ 9 ] . For example , a narrative review on diabetes ( such as that which might be found in a textbook chapter ) might include sections on the physiology and pathophysiology of carbohydrate , lipid , and protein metabolism ; the epidemiology of and prognosis associated with diabetes ; diagnostic and screening approaches ; and preventive , therapeutic , rehabilitative , and palliative interventions . Thus , narrative review s may be most useful for obtaining a broad perspective on a topic ; they are less often useful in furnishing quantitative answers to specific clinical questions . Narrative review s are appropriate for describing the history or development of a problem and its management . Narrative review s may better describe cutting-edge developments if research is scant or preliminary or if studies are very limited by flawed design or execution [ 13 ] . They may be particularly useful for discussing data in light of underlying theory and context . Narrative review s can draw analogies and can conceptually integrate two independent fields of research , such as
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 .