Validity time of normal results of preoperative tests for surgical reintervention and the impact on postoperative outcomes

BACKGROUND AND OBJECTIVE: There are few data defining the period of time in which preoperative tests can be considered valid. The purpose of this study was to determine the likelihood of changes in the results of preoperative tests previously normal in relation to time, and the impact of these changes on postoperative outcomes. METHODS: A total of 970 patients with normal preoperative tests before the first surgery and who required a new intervention were included. The preoperative tests performed for the first procedure were compared with those performed for the second procedure. The following variables were assessed regarding their potential to induce changes in test results: sex, age, surgical risk, previous chemotherapy or radiotherapy, and presence of comorbidities. In-hospital outcomes were analyzed. RESULTS: The median time between procedures was 27 months (6–84). The probability of change in at least one of the preoperative exams was 1.7% (95% CI: 0.5–2.9), 3.6% (95% CI: 1.8–5.4), and 6.4% (95% CI: 3.9–8.9) during the 12, 24, and 36-month intervals, respectively, for patients aged <50 years and 2.1% (95% CI: 0.7–3.5), 9.2% (95% CI: 5.9–12.5), and 13.4% (95% CI: 9.3–17.5), respectively, for patients ≥50 years of age. Age (p = 0.009), surgical risk (p < 0.001), chemotherapy (p = 0.001), radiotherapy (p = 0.012), and comorbidities (p < 0.001) were associated with the likelihood of changes in test results. Test changes were not significantly associated with in-hospital adverse outcomes (p = 0.426). CONCLUSION: For patients undergoing a second surgical procedure, the probability of change in previously normal preoperative tests is low during the first years after the first surgical intervention, and when changes occurred, they did not adversely affect the in-hospital postoperative outcomes.