Postoperative infection and mortality following elective surgery in the International Surgical Outcomes Study (ISOS).

BACKGROUND: Postoperative infection is one of the most frequent and important complications after surgery. The epidemiology of infection following elective surgery remains poorly described. METHODS: This was a prospective analysis of the International Surgical Outcomes Study (ISOS) describing infection by 30 days after elective surgery. Associations between postoperative infection (primary outcome) and baseline demographic, surgical, and anaesthetic risk factors were assessed. Analyses were carried out using logistic and linear regression models. Secondary outcomes were 30-day mortality and duration of hospital stay. Treatments received by patients after different types of infection were evaluated. RESULTS: Some 44 814 patients were included in the analysis, with a total of 4032 infections occurring in 2927 patients (6.5 per cent). Overall, 206 patients died, of whom 99 of 2927 (3.4 per cent) had infection. Some 737 of 4032 infections (18.3 per cent) were severe; the most frequent types were superficial surgical-site infection (1320, 32.7 per cent), pneumonia (708, 17.6 per cent), and urinary tract infection (681, 16.9 per cent). Excluding missing data, antimicrobials were used in 2126 of 2749 infections (77.3 per cent), and 522 of 2164 patients (24.1 per cent) required admission to critical care. Factors associated with an increased incidence of infection in adjusted analyses were: age, male sex, ASA grade, co-morbid disease, preoperative anaemia, anaesthetic technique, surgical category, surgical severity, and cancer surgery. Infection significantly increased the risk of death (odds ratio 4.68, 95 per cent c.i. 3.39 to 6.47; P < 0.001), and duration of hospital stay by on average 6.45 (6.23 to 6.66) days (P < 0.001). CONCLUSION: Infection is a common complication after elective surgery. Recognition of modifiable risk factors will help inform appropriate prevention strategies.

The surgical safety checklist and patient outcomes after surgery: a prospective observational cohort study, systematic review and meta-analysis.

BACKGROUND: The surgical safety checklist is widely used to improve the quality of perioperative care. However, clinicians continue to debate the clinical effectiveness of this tool. METHODS: Prospective analysis of data from the International Surgical Outcomes Study (ISOS), an international observational study of elective in-patient surgery, accompanied by a systematic review and meta-analysis of published literature. The exposure was surgical safety checklist use. The primary outcome was in-hospital mortality and the secondary outcome was postoperative complications. In the ISOS cohort, a multivariable multi-level generalized linear model was used to test associations. To further contextualise these findings, we included the results from the ISOS cohort in a meta-analysis. Results are reported as odds ratios (OR) with 95% confidence intervals. RESULTS: We included 44 814 patients from 497 hospitals in 27 countries in the ISOS analysis. There were 40 245 (89.8%) patients exposed to the checklist, whilst 7508 (16.8%) sustained ≥1 postoperative complications and 207 (0.5%) died before hospital discharge. Checklist exposure was associated with reduced mortality [odds ratio (OR) 0.49 (0.32-0.77); P<0.01], but no difference in complication rates [OR 1.02 (0.88-1.19); P=0.75]. In a systematic review, we screened 3732 records and identified 11 eligible studies of 453 292 patients including the ISOS cohort. Checklist exposure was associated with both reduced postoperative mortality [OR 0.75 (0.62-0.92); P<0.01; I2=87%] and reduced complication rates [OR 0.73 (0.61-0.88); P<0.01; I2=89%). CONCLUSIONS: Patients exposed to a surgical safety checklist experience better postoperative outcomes, but this could simply reflect wider quality of care in hospitals where checklist use is routine.

Meta-analysis of the association between preoperative anaemia and mortality after surgery.

BACKGROUND: Numerous published studies have explored associations between anaemia and adverse outcomes after surgery. However, there are no evidence syntheses describing the impact of preoperative anaemia on postoperative outcomes. METHODS: A systematic review and meta-analysis of observational studies exploring associations between preoperative anaemia and postoperative outcomes was performed. Studies investigating trauma, burns, transplant, paediatric and obstetric populations were excluded. The primary outcome was 30-day or in-hospital mortality. Secondary outcomes were acute kidney injury, stroke and myocardial infarction. Predefined analyses were performed for the cardiac and non-cardiac surgery subgroups. A post hoc analysis was undertaken to evaluate the relationship between anaemia and infection. Data are presented as odds ratios (ORs) with 95 per cent c.i. RESULTS: From 8973 records, 24 eligible studies including 949 445 patients were identified. Some 371 594 patients (39·1 per cent) were anaemic. Anaemia was associated with increased mortality (OR 2·90, 2·30 to 3·68; I(2) = 97 per cent; P < 0·001), acute kidney injury (OR 3·75, 2·95 to 4·76; I(2) = 60 per cent; P < 0·001) and infection (OR 1·93, 1·17 to 3·18; I(2) = 99 per cent; P = 0·01). Among cardiac surgical patients, anaemia was associated with stroke (OR 1·28, 1·06 to 1·55; I(2) = 0 per cent; P = 0·009) but not myocardial infarction (OR 1·11, 0·68 to 1·82; I(2) = 13 per cent; P = 0·67). Anaemia was associated with an increased incidence of red cell transfusion (OR 5·04, 4·12 to 6·17; I(2) = 96 per cent; P < 0·001). Similar findings were observed in the cardiac and non-cardiac subgroups. CONCLUSION: Preoperative anaemia is associated with poor outcomes after surgery, although heterogeneity between studies was significant. It remains unclear whether anaemia is an independent risk factor for poor outcome or simply a marker of underlying chronic disease. However, red cell transfusion is much more frequent amongst anaemic patients.

Kinetic determination of microamounts of some sulphur-containing ligands.

Some sulphur-containing ligands have been shown to inhibit the Hg(II)-catalysed substitution of p-nitrosodiphenylamine (p-NDA) for cyanide in hexacyanoferrate(II), by binding the mercury(II). This effect is used for determination of microamounts of cysteine, thioglycollic acid and thiosulphate. The reactions are followed spectrophotometrically at 640 nm (lambda(max) of [Fe(CN)(5).p-NDA](3-)). The determination range depends on the amount of mercury(II) added and the stability of the Hg(II)-ligand complex. Under specified conditions, the detection limits are: thioglycollic acid 1 x 10(-7)M, cysteine 1 x 10(-6)M and thiosulphate 4 x 10(-7)M.

Trace element determination in environmental pollution: A kinetic method for mercury estimation.

A method is developed for the estimation of mercury in trace concentrations by measuring spectrophotometrically its catalytic effect on the rate of substitution of p-nitrosodiphenylamine into hexacyanoferrate(II). Under the specified conditions the detection limit is found to be 2.0 x 10(-8)M relative standard deviation 1.4%. The effect of other ions is discussed.