Study designs of evaluations included in the review
The authors seem to have searched for single case reports and case series.
Specific interventions included in the review
Metformin therapy given at a dose ranging from 0.5 to 2.85 g/day (where reported) for a duration of 1 week to 15 years (where reported).
Participants included in the review
People receiving metformin therapy for a range of indications. The people included in the review had the following conditions: asthma, chronic cardiac and renal failure, end-stage liver failure, pneumonia, acute renal failure, chronic dialysis therapy, postsurgical shock syndrome, severe heart failure, and intestinal occlusion. The mean age of the included participants was 60.9 years
Outcomes assessed in the review
Recorded cases of 'metformin-associated lactic acidosis' were sought. Reports of lactic acidosis secondary to metformin overdosage or contrast media-induced renal failure in metformin-treated patients were excluded. From the publications reviewed, the link between metformin and lactic acidosis was assessed according to the following criteria: lactic acidosis, metformin accumulation, and the presence of concurrent pathologies.
How were decisions on the relevance of primary studies made?
The authors do not state how the papers were selected for the review, or how many of the reviewers performed the selection.