BackgroundAccurate, short, cognitive screening instruments are important for identifying mild cognitive impairment (MCI) and dementia including Alzheimer's disease. The Quick Mild Cognitive Impairment (Qmci) screen, given its brevity, may be useful in this setting but it has not been validated in Spanish.ObjectiveTo compare the diagnostic accuracy of the Spanish version (Qmci-S) to the Montreal Cognitive Assessment (MoCA).MethodsPatients aged ≥55 years were recruited from six Primary Care Teams in Barcelona, Spain, between 2018-2019. Dementia, MCI, and normal cognition (NC) were classified following neuropsychological testing, independent of the Qmci-S and MoCA scores. Diagnostic accuracy was determined by the area under receiver operating characteristic curves (AUC), adjusted for age and education.ResultsIn total, 337 patients were included, mean 77.9 years, standard deviation (SD) ± 6.9. Most were female (57.3%). The intraclass correlation coefficient for the Qmci-S was excellent (0.98). The Qmci-S had good to excellent diagnostic accuracy for separating NC from MCI and dementia (AUC 0.91) and was statistically greater than the MoCA (AUC 0.86), p = 0.029. Accuracy was similar for differentiating NC from MCI and MCI from dementia. The Qmci-S had a shorter administer time, mean 8.6 (±3.2) versus 12.75 (SD ±5.5) minutes, respectively, p < 0.001.ConclusionsThe newly developed Qmci-S screen showed excellent criterion, construct and concurrent validity versus the widely used MoCA and had statistically similar, good to excellent, diagnostic accuracy for cognitive impairment. Its significantly shorter administration time suggests it may be the better screen in a Spanish speaking population in primary care, though further research is required.