Cautionary tales in the interpretation of systematic reviews of therapy trials

Systematic reviews: Separating fact from fiction

The volume of scientific literature continues to expand and decision-makers are faced with increasingly unmanageable volumes of evidence to assess. Systematic reviews (SRs) are powerful tools that aim to provide comprehensive, transparent, reproducible and updateable summaries of evidence. SR methods were developed, and have been employed, in healthcare for more than two decades, and they are now widely used across a broad range of topics, including environmental management and social interventions in crime and justice, education, international development, and social welfare. Despite these successes and the increasing acceptance of SR methods as a 'gold standard' in evidence-informed policy and practice, misconceptions still remain regarding their applicability. The aim of this article is to separate fact from fiction, addressing twelve common misconceptions that can influence the decision as to whether a SR is the most appropriate method for evidence synthesis for a given topic. Through examples, we illustrate the flexibility of SR methods and demonstrate their suitability for addressing issues on environmental health and chemical risk assessment.

Systematic Reviews Informing Occupational Therapy

OBJECTIVE. We sought to identify and describe the number, topics, and publishing trends of systematic reviews relevant to occupational therapy indexed in the OTseeker database.

METHOD. We performed a cross-sectional survey of the systematic reviews contained in OTseeker in December 2011.

RESULTS. Of the 1,940 systematic reviews indexed in OTseeker, only 53 (2.7%) were published in occupational therapy journals. The most common diagnostic categories were stroke (n = 195, 10.1%) and affective disorders (n = 204, 10.5%). The most common intervention categories were consumer education (n = 644, 33.2%) and psychosocial techniques (n = 571, 29.4%). Only 390 (20.1%) of the 1,940 systematic reviews specifically involved occupational therapy.

CONCLUSION. Occupational therapists need to search broadly to locate relevant systematic reviews or, alternatively, to use databases such as OTseeker. Clarity about the involvement of occupational therapy in reports of future research will improve the ability to identify occupational therapy research for all stakeholders. Finally, occupational therapy practitioners need to read systematic reviews critically to determine whether review conclusions are justified.

Insulin versus an oral antidiabetic agent as add-on therapy in type 2 diabetes after failure of an oral antidiabetic regimen: a meta-analysis

BACKGROUND

Although evidence-based guidelines for the treatment of type 2 diabetes mellitus provide clear recommendations for initial therapy, evidence on an optimal treatment strategy after secondary failure is unclear.

PURPOSE

To compare the efficacy of add-on therapy using basal insulin versus an additional oral antidiabetic agent in patients with type 2 diabetes and secondary failure.

DATA SOURCES

We searched the following electronic databases from inception until June 2007: MEDLINE; EMBASE; Cochrane Central Register of Controlled Trials; Web of Science; Scopus; CINAHL; International Pharmaceutical Abstracts; Academic OneFile; PASCAL; Global Health Database; LILACS; HealthSTAR; PubMed. Reference lists of potentially relevant articles and clinical trial databases were searched, pharmaceutical manufacturers were contacted, and grey literature sources were sought.

STUDY SELECTION

Randomized controlled trials (RCTs) involving subjects with type 2 diabetes with secondary failure who were randomly assigned to receive additional basal insulin therapy (insulin glargine, detemir, or NPH [neutral protamine Hagedorn]) versus another oral antidiabetic agent from any class.

DATA EXTRACTION

Two reviewers independently screened articles, extracted data and assessed methodological quality. Our primary outcome was glycemic control measured by change in glycosylated hemoglobin (Hb(A1C)) and the proportion of subjects achieving a Hb(A1C) value of ≤ 7%.

DATA SYNTHESIS

To compare overall efficacy between the 2 treatment strategies, change in Hb(A1C) was pooled across studies using a random-effects model and weighted mean difference (WMD). Eleven RCTs, involving 757 participants with a median age of 56 and a median known duration of diabetes of 11 years, were included in our analysis. Insulin treatment demonstrated a small but statistically significant improvement in Hb(A1C) compared with the use of an additional oral agent as add-on therapy (WMD -0.17; 95% CI [confidence interval] -0.33 to -0.02).

LIMITATIONS

The use of surrogate outcomes and the short duration of the trials makes it impossible to gain information on long-term patient-oriented outcomes. The overall quality of the studies was low, primarily in view of inadequate blinding.

CONCLUSIONS

Although add-on therapy using injected insulin shows a slight benefit over an additional oral antidiabetic agent, our results indicate that basal insulin therapy and the use of an oral agent as add-on therapy produce comparable results. Non-therapeutic differences must be considered in the choice of treatment strategies. More high-quality studies with adequate safety data using more aggressive insulin titrations are needed.