Definition and application of neuropsychological test battery to evaluate postoperative cognitive dysfunction

To investigate the adequacy of the neuropsychological test battery proposed by the International Study of Postoperative Cognitive Dysfunction to evaluate this disorder in Brazilian elderly patients undergoing surgery under general anesthesia.

A neuropsychological assessment was made in patients undergoing non-cardiac surgery under general anesthesia, aged over 65 years, literate, with no history of psychiatric or neurological problems and score on the Mini Mental State Examination at or above the cutoff point for the Brazilian population (>18 or >23) according to the schooling level of the subject. Eighty patients were evaluated by a trained team of neuropsychologists up to 24 hours before elective surgery.

Among the patients evaluated, one was excluded due to score below the cutoff point in the Mini Mental State Examination and two did not complete the test battery, thus remaining 77 patients in the study. The mean age was 69±7.5 years, and 62.34% of the subjects had ±4 years of study. The subjects had significantly lower averages than expected (p<0.001) for normative tables on neuropsychological tests.

The study demonstrated the applicability of the instruments in the Brazilian elderly and low schooling level population, but suggested the need to determine cutoff points appropriate for these individuals, ensuring the correct interpretation of results. This battery is relevant to postoperative follow-up evaluations, favoring the diagnosis of postoperative cognitive dysfunction in patients undergoing different types of surgery and anesthetic techniques.