A systematic review of propensity score methods in the acute care surgery literature: avoiding the pitfalls and proposing a set of reporting guidelines.

BACKGROUND: Propensity score methods are techniques commonly employed in observational research to account for confounding when estimating the effects of treatments and exposures. These methods have been increasingly employed in the acute care surgery literature in an attempt to infer causality; however, the adequacy of reporting and the appropriateness of statistical analyses when using propensity score matching remain unclear. OBJECTIVES: The goal of this systematic review is to assess the adequacy of reporting of propensity score methods, with an emphasis on propensity score matching (to assess balance and the use of appropriate statistical tests), in acute care surgery (ACS) studies and to provide suggestions for improvement for junior investigators. METHODS: We searched three databases, and other relevant literature (from January 2005 to June 2015) to identify observational studies within the ACS literature using propensity score methods (PROSPERO No: CRD42016036432). Two reviewers extracted data and assessed the quality of the studies retrieved by reviewing the adequacy of both overall reporting and of the propensity score matching methods used. RESULTS: A total of 49/71 (69%) of studies adequately reported propensity score methods overall. Matching was the most common propensity score method used in 46/71 (65%) studies, with 36/46 (78%) studies reporting matching methods adequately. Only 19/46 (41%) of matching studies reported the balance of baseline characteristics between treated and untreated subjects while 6/46 (13%) used correct statistical methods to assess balance. There were 35/46 (76%) of matching studies that explicitly used statistical methods appropriate for the analysis of matched data when estimating the treatment effect and its statistical significance. CONCLUSION: We have proposed reporting guidelines for the use of propensity score methods in the acute care surgery literature. This is to help investigators improve the adequacy of reporting and statistical analyses when using observational data to estimate effects of treatments and exposures.

Pre-operative plasma levels of vascular endothelial growth factor A, C and D in patients with colorectal cancer.

AIMS: Vascular endothelial growth factor (VEGF)-C and VEGF-D are angiogenic and lymphangiogenic members of the VEGF family of growth factors. Increased VEGF-C or VEGF-D expression in human tumours may be associated with lymph-node metastasis and lymphatic invasion. Circulating plasma levels of VEGF-A, VEGF-C and VEGF-D were measured in patients with colorectal cancer, and assessed for their usefulness as a diagnostic tool for determining lymph-node metastasis. MATERIALS AND METHODS: One hundred and twenty patients with colorectal cancer and 50 healthy control patients were included in the study. Plasma growth-factor levels were assessed by enzyme-linked immunosorbent assays. RESULTS: No significant differences in plasma VEGF-C or VEGF-D levels were seen between patients subgrouped by clinicopathological variables. In particular, there were no differences in median plasma VEGF-C or VEGF-D level in patients with and without lymph-node involvement (VEGF-C: 11.2 U/ml [range, 4.9-51.9] vs 9.9 U/ml [4.4-93.4 U/ml]; P = 0.90; VEGF-D: 335 pg/ml [113-1102] vs 316.5 pg/ml [0-1343]; P = 0.68). CONCLUSIONS: Circulating plasma levels of VEGF-C and VEGF-D do not allow pre-operative identification of lymph-node status in patients with colorectal cancer.

Waiting times for treatment of rectal cancer in North West England.

An interim goal of the NHS National Cancer Plan is that, by 2005, patients with cancer should be treated within one month of diagnosis and within two months from urgent general practitioner referral. Preoperative radiotherapy for rectal cancer reduces the risk of local recurrence and may translate into improved patient survival. We conducted a prospective audit of existing waiting times for preoperative radiotherapy experienced by 65 patients with rectal cancer referred to the Christie Cancer Centre, Manchester, UK, between May and November 2002. The median time between referral from the surgeon to the start of radiotherapy was 40 days (range 11-85). Only 4 patients (6%) received radiotherapy within 28 days of referral by the surgeon. 62 patients (95%) underwent surgery within 14 days of completing radiotherapy. Delays in the provision of preoperative radiotherapy were primarily due to shortages of radiography staff and equipment. Lack of such infrastructure will prove a major stumbling block to achieving the targets of the NHS Cancer Plan.