June Cochrane review round-up
medwireNews: Here we provide an overview of the seven Cochrane reviews published in June that covered topics relating to diabetes, including glycemic control for prevention of renal failure, phototherapy for foot ulcers, and anti-vascular endothelial growth factor (VEGF) treatment for diabetic macular edema.
The largest review, which included 11 studies with 29,141 participants in its meta-analysis, highlights the continued lack of evidence to support specific blood glucose targets to prevent kidney failure in people with diabetes.
Patients allocated to tight glycemic control (glycated hemoglobin <7.0% or fasting glucose <120 mg/dL) had significant reductions in the onset of microalbuminuria and progression to macroalbuminuria, but the reviewers stress that these are surrogate measures of kidney damage and the changes are therefore “of uncertain future clinical significance.”
There was no effect of tight glycemic control on kidney failure defined as a doubling of serum creatinine or end-stage kidney disease, or on mortality; however, the reviewers note that the studies lasted between 5 and 10 years, whereas these endpoints “tend to accrue at 10 to 20 years after diagnosis” of diabetes.
Another review – a network meta-analysis – compared the efficacy of the currently available anti-VEGF treatments for diabetic macular edema: aflibercept, bevacizumab, and ranibizumab. Using data from 24 studies with 6007 participants, the reviewers found all three medications to be more effective than laser therapy, with around three in 10 versus one in 10 people improving their vision by three lines or more after 1 year.
The analysis also suggests that aflibercept is more effective than bevacizumab or ranibizumab over 1 year of treatment, with patients given the latter two medications significantly less likely to achieve a three-line vision improvement.
The authors of these two reviews had a large amount of relatively high-quality data at their disposal. Those conducting the other reviews published last month had to work with data from smaller, lower-quality studies, inhibiting their ability to draw sound conclusions.
One of these reviews was of glucose monitoring in pregnant women. It included 10 trials involving 538 women with pre-existing type 1 or type 2 diabetes, whose blood glucose was monitored by means including self-monitoring, hospital care, pre- or post-prandial monitoring, automated telemedical monitoring, and continuous glucose monitoring.
The reviewers found no evidence to support one form of glucose monitoring over any other, but also report that the evidence quality was almost all low or very low.
Two reviews looked at diabetic foot ulcers, with one assessing phototherapy and the other rounding up the evidence for topical antimicrobial agents. Both reviews were, again, based on low-quality evidence, but both found some evidence of benefit. Across eight trials, phototherapy appeared to increase the proportion of wounds completely healed and reduce wound size. There were 22 trials of topical antimicrobial agents, but these were so heterogeneous that the reviewers were frequently unable to pool the data. They did, however, identify a possible benefit for antimicrobial dressings versus non-antimicrobial dressings.
There were also two reviews of behavior-changing interventions to tackle obesity in adolescent and preadolescent children. You can read our full report of those reviews here.
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