A systematic review: comparative analysis of the effects of propofol and sevoflurane on postoperative cognitive function in elderly patients with lung cancer

Background The potential risk for cognitive impairment following surgery and anesthesia is a common concern, especially in the elderly and more fragile patients. The risk for various neurocognitive effects is thus an area of importance. The independent impact of surgery and anesthesia is still not known. Likewise, the independent effect of different drugs used during anesthesia is a matter of debate, as is the number and amounts of drugs used and the “depth of anesthesia.” So, understanding the drug-related phenomenon and mechanisms for postoperative cognitive impairment is essential. This meta-analysis aims to compare the effects of propofol and sevoflurane anesthesia on postoperative cognitive function in elderly patients with lung cancer. Methods This study is a systematic review and meta-analysis for controlled clinical studies. Public-available online databases were searched to identify eligible randomized placebo-controlled trials or prospective cohort studies concerning the effects of propofol and sevoflurane on postoperative cognitive function. The primary endpoints are postoperative mini-mental state examination (MMSE) scores at various time points; the secondary endpoint is the serum S100beta concentration 24 h after surgery. Standard mean differences (SMDs) along with 95% confidence intervals (CIs) were extracted and analyzed using random or fixed-effects models. Analyses regarding heterogeneity, risk of bias assessment, and sensitivity were performed. Results We searched 1626 eligible publications and 14 studies of 1404 patients were included in the final analysis. The majority of included studies had been undertaken in Asian populations. Results suggested that propofol has a greater adverse effect on cognitive function in the elderly patients with lung cancer than sevoflurane. There were significant differences in issues of MMSE 6 h (11 studies; SMD -1.391, 95% CI -2.024, − 0.757; p < 0.001), MMSE 24 h (14 studies; SMD -1.106, 95% CI -1.588, − 0.624; p < 0.001), MMSE 3d (11 studies; SMD -1.065, 95% CI -1.564, − 0.566; p < 0.001), MMSE 7d (10 studies; SMD -0.422, 95% CI -0.549, − 0.295; p < 0.001), and serum S100beta concentration at 1 day after surgery (13 studies; SMD 0.746, 95% CI 0.475, 1.017; p < 0.001). Conclusion Propofol has a more significant adverse effect on postoperative cognitive function in elderly patients with lung cancer than sevoflurane.