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The following is a summary of “Informant accuracy of IQCODE, AD8 and GPCOGi for diagnosis of dementia: does your friend know best?” published in the April 2025 issue of BMC Primary Care by Chingono et al. 

Researchers conducted a retrospective study to evaluate the accuracy of informant questionnaires in primary care for dementia diagnosis. 

The diagnostic accuracy of IQCODE, AD8, and GPCOGi was assessed based on the informant’s relation m ship to the patient. A total of 240 participants were recruited from 21 general practices in South West England. The reference standard for dementia diagnosis was made by a specialist clinician using ICD-10 criteria. A threshold of greater than 3.3 on IQCODE, greater than or equal to 2 on AD8, and less than 5 on the informant component of GPCOG indicated an abnormal test. 

The results showed that of 238 participants with informant data, 131 had dementia, 60 had CIND, and 47 had normal cognition. Median informant age was 70 years (IQR 60 to 78). 71% of informants were female, and 56% were spouses. Compared to spouses, adult descendants scored participants more cognitively impaired, while friends scored less impaired. After full adjustment, there was little evidence of difference by informant type. Sensitivity ranged from 91 to 100% for IQCODE, 94–100% for AD8, and 99–100% for GPCOGi. Specificity ranged from 25 to 79% for IQCODE, 13–75% for AD8, and 17–38% for GPCOGi. Adult descendants had the lowest specificity: 25% (95% CI 10–47%) for IQCODE, 13% (95% CI 3–32%) for AD8, and 17% (95% CI 5–37%) for GPCOGi. Friends had the highest specificity: 79% (95% CI 49–95%) for IQCODE, 75% (95% CI 48–93%) for AD8, and 38% (95% CI 15–64%) for GPCOGi. 

Investigators found that informants of any relationship type, using IQCODE, AD8, or GPCOGi, were useful for ruling out dementia but not for ruling it in. No evidence of difference was found between spouses or adult descendants, but friends performed significantly better overall on IQCODE and AD8. 

Source:bmcprimcare.biomedcentral.com/articles/10.1186/s12875-025-02745-w