Clock drawing test: comparison between the Pfizer and the Shulman systems

Dement Neuropsychol. 2021 Oct-Dec;15(4):480-484. doi: 10.1590/1980-57642021dn15-040009.

Abstract

Cognitive decline can be screened by the clock drawing test (CDT), which has several versions.

Objective: This survey aimed to analyze the correlation between two simple methods for scoring the CDT.

Methods: This cross-sectional study was nested in the Elo-Creati cohort from Passo Fundo, Brazil and comprised 404 subjects. Two raters underwent previous training and scored the subjects' CDT according to both the Pfizer and Shulman systems. The inter-observer and intra-observer concordance within each method was analyzed with the Spearman's rank correlation coefficient, as well as the concordance of the scores between the two methods. Age and scholarity were also correlated with the scores.

Results: Most of the participants were women (93.8%) and Caucasian (84.6%), with a mean age of 66.9 (±7.8) years and a scholarity of 10.9 years (±5.6). There was significant inter-observer (Pfizer: r=0.739, p£0.001; Shulman: r=0.727, p£0.001) and intra-observer correlation (Pfizer: rater 1, r=0.628, p≤0.001; rater 2, r=0.821, p≤0.001; Shulman: rater 1, r=0.843, p≤0.001; rater 2: r=0.819; p≤0.001). Intra-observer correlation was also observed comparing Pfizer and Shulman methods (rater 1: r=0.744; p≤0.001; rater 2: r=0.702; p≤0.001). There was weak correlation of the scores with scholarity (Pfizer: r=0.283, p£0.001; Shulman: r=0.244, p£0.001) and age (Pfizer: r=-0.174, p£0.001; Shulman: r=-0.170, p£0.001). More participants were classified with decreased cognition through the Pfizer system (rater 1: 44.3 vs. 26.5%; rater 2: 42.1 vs. 16.3%; p≤0.001).

Conclusions: For this population, our results suggest that the Pfizer system of scoring CDT is more suitable for screening cognitive decline.

O déficit cognitivo pode ser triado pelo teste do desenho do relógio (TDR), que tem várias versões.

Objetivo: Esta pesquisa visou avaliar a concordância entre dois métodos simples de TDR.

Métodos: Estudo transversal, aninhado na coorte Elo-Creati de Passo Fundo, Brasil, que incluiu 404 sujeitos. Dois avaliadores previamente treinados analisaram o TDR dos participantes de acordo com os sistemas de Pfizer e de Shulman. A concordância inter e intraobservador foi analisada com o teste de coeficiente de correlação de postos de Spearman, assim como a concordância pela estatística kappa dos escores entre os métodos. Idade e escolaridade também foram correlacionados com os escores.

Resultados: A maioria dos participantes era de mulheres (93,8%) e caucasianos (84,6%), com média de idade de 66,9±7,8 anos e de escolaridade de 10,9±5,6 anos. Houve significativa correlação interobservador (Pfizer: r=0,739, p£0,001; Shulman: r=0,727, p£0,001) e intraobservador (Pfizer: avaliador 1, r=0,628, p≤0,001; avaliador 2, r=0,821, p≤0,001; Shulman: avaliador 1, r=0,843, p≤0,001; avaliador 2: r=0,819; p≤0,001). Correlação intraobservador significativa também foi evidenciada comparando-se os sistemas de Pfizer e Shulman (avaliador 1: r=0,744; p≤0,001; avaliador 2: r=0,702; p≤0,001). Houve fraca correlação dos escores com escolaridade (Pfizer: r=0,283, p£0,001; Shulman: r=0,244, p£0,001) e idade (Pfizer: r=-0,174, p£0,001; Shulman: r=-0,170, p£0,001). Mais participantes foram classificados com declínio cognitivo com o sistema de Pfizer (avaliador 1: 44,3 vs. 26,5%; avaliador 2: 42,1 vs. 16,3%; p≤0,001).

Conclusões: Nossos resultados sugerem que, para essa população, o sistema de Pfizer para avaliar o TDR é mais adequado para a triagem cognitiva.

Keywords: clock drawing test; cognitive decline; correlation; screening.