Summary of findings 1. Summary of findings: perioperative control for people with diabetes undergoing surgery.
| Perioperative glycaemic control for people with diabetes undergoing surgery | ||||||
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Patients: people with diabetes undergoing surgery Settings: hospital Intervention: intensive blood glucose control Comparison: conventional blood glucose control | ||||||
| Outcomes | Anticipated absolute effects (95% CI) | Relative effect (95% CI) | № of participants (studies) | Certainty of the evidence (GRADE) | Comment | |
| Risk with conventional glucose control a | Risk with intensive glucose control | |||||
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All‐cause mortality (death from any cause) Follow‐up: from 28 days to 1 year |
91 per 1000 | 98 per 1000 (80 to 121) | RR 1.08 (0.88 to 1.33) | 2551 (18) | ⊕⊕⊕⊕ highb,c,d | The pooled relative effect was based on 15 studies; 3 studies could not be included as they had zero events in both the intervention and control groups. |
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Severe hypoglycaemic episodes (number of severe hypoglycaemic episodes) Follow‐up: from 28 days to 1 year |
6 per 1000 | 29 per 1000 (13 to 65) | RR 4.73 (2.12 to 10.55) | 1896 (11) | ⊕⊕⊝⊝ lowc,e,f | The pooled relative effect was based on 8 studies; 3 studies could not be included as they had zero events in both the intervention and control groups. |
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Infectious complications (infectious complication after surgery (e.g. pneumonia, urinary tract infection)) Follow‐up: from 28 days to 1 year |
183 per 1000 | 137 per 1000 (101 to 190) | RR 0.75 (0.55 to 1.04) | 2453 (18) | ⊕⊕⊕⊝ lowc,g,h | The pooled relative effect was based on 16 studies; 2 studies could not be included as they had zero events in both the intervention and control groups. |
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Cardiovascular events (incidents that may cause damage to the cardiovascular system) Follow‐up: from 28 days to 1 year |
244 per 1000 | 178 per 1000 (134 to 237) | RR 0.73 (0.55 to 0.97) | 1454 (12) | ⊕⊕⊕⊝ lowc,h,i | The pooled relative effect was based on 11 studies; one study could not be included as it had zero events in both the intervention and control groups. |
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Renal failure (number of individuals with an elevation of serum creatinine greater than 2 mg/dL or requiring dialysis) Follow‐up: from 28 days to 1 year |
149 per 1000 | 138 per 1000 (103 to 182) | RR 0.92 (0.69 to 1.22) | 2086 (14) | ⊕⊕⊕⊝ lowc,g,j | — |
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Length of ICU stay (days admitted to the ICU unit) Follow‐up: from 28 days to 1 year |
The mean length of ICU stay ranged across control groups from 1.2 to 7.4 days | The mean length of ICU stay in the intervention groups was 0.1 days shorter (0.57 days shorter to 0.38 days longer) | — | 1687 (11) | ⊕⊕⊕⊝ lowh,k |
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Length of hospital stay (days admitted to the hospital) Follow‐up: from 28 days to 1 year |
The mean length of hospital stay ranged across control groups from 5.0 to 19.6 days | The mean length of hospital stay in the intervention groups was 0.79 days shorter (1.79 days shorter to 0.21 days longer) | — | 1520 (12) | ⊕⊕⊝⊝ very lowh,k,l |
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| CI: confidence interval; ICU: intensive care unit; MD: mean difference; RR: risk ratio | ||||||
| GRADE Working Group quality of evidence grades High certainty: we are very confident that the true effect lies close to that of the estimate of the effect Moderate certainty: we are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different Low certainty: our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect Very low certainty: we have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect | ||||||
aMean baseline risk from the included studies.
bNot downgraded for risk of bias: studies with an unclear risk of selection bias did not have major impact on certainty. A sensitivity analysis omitting these studies showed a similar effect estimate (RR 1.09, 95% CI 0.88 to 1.36).
cOptimal information sizes are estimated to assess the precision of the effect estimates according to a threshold of an anticipated 25% relative risk reduction.
dNot downgraded for imprecision: according to the control group event rate (0.1) and an anticipated 25% relative risk reduction, the optimal information size has been reached.
eDowngraded by one level due to the impact of risk of bias: the trial informing the outcome was open for participants and personnel, and many did not provide details on blinding of outcome assessment.
fDowngraded by one level for imprecision: optimal information size probably not met; with a 0.05 control group event rate and an anticipated 25% relative risk reduction, about 3500 participants would be required.
gDowngraded by one level for imprecision: optimal information size probably not met; with a 0.10 control group event rate and an anticipated 25% relative risk reduction, about 3000 participants would be required.
hDowngraded by one level due to risk of bias: all included studies were at an overall high risk of bias.
iDowngraded by one level for imprecision: optimal information size probably not met; with a 0.10 control group event rate and an anticipated 25% relative risk reduction, about 2000 participants would be required.
jDowngraded by one level for indirectness: heterogeneous definition of the outcome measure.
kDowngraded by one level for inconsistency: unexplained statistical heterogeneity within effect estimates from trials informing this outcome (I2 = 69% for length of ICU stay, I2 = 77% for length of hospital stay) with large differences in point estimates.
lDowngraded by one level for imprecision: lower 95% CI boundary includes the possibility of an important benefit.