Associations between postoperative anaemia and unplanned readmission to hospital after major surgery: a retrospective cohort study†

BACKGROUND

Anaemia following major surgery may be associated with unplanned readmission to hospital. However, the severity-response relationship between the degree of anaemia at discharge and the risk of unplanned readmission is poorly defined. We aimed to describe the severity-response relationship between haemoglobin concentration at the time of discharge and the risk of unplanned readmission in a cohort of patients undergoing different types of major surgery.

METHODS

We performed a retrospective cohort study in a single tertiary health service, including all patients who underwent major surgery (orthopaedic, abdominal, cardiac or thoracic) between 1 May 2011 and 1 February 2022. The primary outcome was unplanned readmission to hospital in the 90 days following discharge after the index surgical procedure. These complex, non-linear relationships were modelled with restricted cubic splines.

RESULTS

We identified 22,134 patients and included 14,635 in the primary analysis, of whom 1804 (12%) experienced at least one unplanned readmission. The odds of unplanned readmission rose when the discharge haemoglobin concentration was < 100 g.l-1 (p < 0.001). On subgroup analysis, the haemoglobin threshold below which odds of readmission began to increase appeared to be higher in patients undergoing emergency surgery (110 g.l-1; p < 0.001) compared with elective surgery. Declining discharge haemoglobin concentration was associated with increased odds ratios (95%CI) of unplanned readmission in patients undergoing orthopaedic (1.08 (1.01-1.15), p = 0.03), abdominal (1.13 (1.07-1.19), p < 0.001) and thoracic (1.12 (1.01-1.24), p = 0.03) procedures, but not cardiac surgery (1.09 (0.99-1.19), p = 0.07).

CONCLUSIONS

Our findings suggest that a haemoglobin concentration < 100 g.l-1 following elective procedures and < 110 g.l-1 following emergency procedures, at the time of hospital discharge after major surgery, was associated with unplanned readmission. Future interventional trials that aim to treat postoperative anaemia and reduce unplanned readmission should include patients with discharge haemoglobin below these thresholds.

Hypocalcemia in trauma patients: A systematic review

BACKGROUND

During hemorrhagic shock and subsequent resuscitation, pathways reliant upon calcium such as platelet function, intrinsic and extrinsic hemostasis, and cardiac contractility are disrupted. The objective of this systematic review was to examine current literature for associations between pretransfusion, admission ionized hypocalcemia, and composite outcomes including mortality, blood transfusion requirements, and coagulopathy in adult trauma patients.

METHODS

This review was reported using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist. We searched Ovid MEDLINE and grey literature from database inception till May 3, 2020. Case series and reports were excluded. Reference lists of appraised studies were also screened for articles that the aforementioned databases might not have captured. The Newcastle-Ottawa Scale was used to assess study quality.

RESULTS

A total of 585 abstracts were screened through database searching and alternative sources. Six unique full-text studies were reviewed, of which three were excluded. Admission ionized hypocalcemia was present in up to 56.2% of the population in studies included in this review. Admission ionized hypocalcemia was also associated with increased mortality in all three studies, with increased blood transfusion requirements in two studies, and with coagulopathy in one study.

CONCLUSION

Hypocalcemia is a common finding in shocked trauma patients. While an association between admission ionized hypocalcemia and mortality, blood transfusion requirements, and coagulopathy has been identified, further prospective trials are essential to corroborating this association.

LEVEL OF EVIDENCE

Systematic review, level III.

Mutagenic and recombinogenic activity of hydrazine sulphate in Saccharomyces cerevisiae

Treatment of diploid cells of S. cerevisiae with 0.1 and 0.2 M hydrazine sulphate induced reverse mutation, mitotic crossing-over and gene conversion at exposures ranging over 4 orders of magnitude. The percentage of induced mitotic cross-overs and total aberrant colonies as well as the frequencies of revertants and convertants were dependent on the concentration used and the duration of treatment. These genetic events are induced without post-treatment cell division and at exposures which cause a minimal level of cell death.