Methods for studying adverse events on surgical wait lists

Abstract

Studies on access to health care are often interested in determining the relationship between the length of delay and the risk of adverse events while waiting. When access to elective surgery is rationed by wait lists, patients requiring and suitable for the operation are subject to competing events of surgery, pre-operative death, unplanned emergency admission or cancellation of surgery for other reasons. Methodologically, measuring the probability of adverse events in patients on wait lists for treatment is similar to quantifying the risk of an event during follow-up in a population exposed to competing risks. Although the Kaplan-Meier method is commonly used to summarize the probability of a primary event, such as death before surgery or unplanned emergency admission, over wait-list time, the estimates produced by this method are only interpretable in a hypothetical situation when all competing risks are eliminated without altering the risk of primary event. In this paper, we consider two other measures for summarizing wait-list data-cumulative incidence and conditional probability function of a competing event. To describe application of these methods in studying outcomes of delaying on surgical wait lists, Robert Hayden-for the Surgical Research Committee of the British Columbia Cardiac Registries, contributing surgeons are listed at the end of the paper. Ó Springer Science+Business Media, LLC 2006we used data from a population-based prospective registry which collects the information on access to elective bypass surgery. The summary probabilities were quantified separately in two groups: high-severity at presentation were patients with either persistent unstable angina or stable angina and extensive coronary artery disease, and low-severity at presentation were stable symptomatic patients with limited disease. Our results suggest that the protracted delay for surgical revascularization carries a significant risk of death even in cardiac surgery patients judged to be low-severity at presentation.

The occurrence of adverse events in relation to time after registration for coronary artery bypass surgery: a population-based observational study

“…death) instead of competing events (e.g. planned surgery) by a certain time on the wait list [22,23]. Both the event rate and the probability of remaining on the list influence the CIF.…”

Patient safety as a public health problem

“…The risk of unwanted outcomes in people who demand health services increases also as a result of untimely or delayed access to care. The consequences for people who have to wait in order to receive needed care can be devastating, as delayed treatment can lead to worsening of preexisting or acute conditions that may result in a worse health outcome or the need for potentially more complex procedures (40)(41)(42)(43).…”

Transforming Health Care Scheduling and Access

“…Extended wait times and delays for care have been shown to negatively affect morbidity, mortality, and the quality of life via a variety of health issues, including cancer (Christensen et al, 1997;Coates, 1999;Waaijera et al, 2003); heart disease (Cesena et al, 2004;Sobolev et al, 2006aSobolev et al, ,b, 2012Sobolev et al, , 2013; hip (Garbuz et al, 2006;Moja et al, 2012;Simunovic et al, 2010;Smektala et al, 2008) and knee problems (Desmeules et al, 2012;Hirvonen et al, 2007); spinal fractures (Braybrooke et al, 2007); and cataracts of the eye (Boisjoly et al, 2010;Conner-Spady et al, 2007;Hodge et al, 2007). The timely delivery of appropriate care has also been shown to reduce the mortality and morbidity associated with a variety of medical conditions, including kidney disease and mental health and addiction issues (Gallucci et al, 2005;Hoffman et al, 2011;Smart and Titus, 2011).…”