Detection and Prediction of Incident Alzheimer Dementia over a 10-Year or Longer Medical History: A Population-Based Study in Primary Care

Background: Despite the crucial role played by general practitioners in the identification and care of people with cognitive impairment, few data are available on how they may improve the early recognition of patients with Alzheimer dementia (AD), especially those with long (i.e., 10 years and longer) medical history. Aims: To investigate the occurrence and the predictors of AD during a 10-year or longer period prior AD diagnosis in primary care patients aged 60 years or older. Materials and Methods: A cohort study with a nested case-control analysis has been conducted. Data were extracted from the Italian Health Search Database (HSD), an Italian database with primary care data. AD cases have been defined in accordance with the International Classification of Diseases, ninth edition (ICD-9-CM) codes and coupled with the use of anti-dementia drugs. Prevalence and incidence rates of AD have been calculated. To test the association between candidate predictors, being identified in a minimum period of 10 years, and incident cases of AD, we used a multivariate conditional logistic regression model. Results: As recorded in the primary care database, AD prevalence among patients aged 60 years or older was 0.8% during 2016, reaching 2.4% among nonagenarians. Overall, 1,889 incident cases of AD have been identified, with an incidence rate as high as 0.09% person-year. Compared with 18,890 matched controls, history of hallucinations, agitation, anxiety, aberrant motor behavior, and memory deficits were positively associated with higher odds of AD (p < 0.001 for all) diagnosis. A previous diagnosis of depression and diabetes and the use of low-dose aspirin and non-steroidal anti-inflammatory drugs were associated with higher odds of AD (p < 0.05 for all). Conclusion: Our findings show that, in accordance with primary care records, 1% of patients aged 60 years and older have a diagnosis of AD, with an incident AD diagnosis of 0.1% per year. AD is often under-reported in primary care settings; yet, several predictors identified in this study may support general practitioners to early identify patients at risk of AD.