Characterising patients in England with Down syndrome and Alzheimer's disease: a descriptive observational study using data from Clinical Practice Research Datalink linked to Hospital Episode Statistics.

OBJECTIVES

To characterise demographics, comorbidities, co-medications and healthcare resource utilisation in patients with Down syndrome (DS) who were newly diagnosed with Alzheimer’s disease (AD) and patients from the general population who were newly diagnosed with AD. To explore potential descriptive differences between these cohorts.

DESIGN

Descriptive observational study.

SETTING

Real-world data in England from the Clinical Practice Research Datalink Aurum primary care database linked to the Hospital Episode Statistics secondary care database.

PARTICIPANTS

Two previously published disease-based algorithms and one previously published medication-based algorithm were selected to identify patients newly diagnosed with AD using an index period from 01 January to 31 December 2019. Patients were organised into three ‘general AD’ cohorts (Cohorts A, B and C), each defined using one of these three algorithms. Three corresponding DS-associated AD (DS-AD) subcohorts were then identified by selecting patients within each cohort who also had a DS diagnosis. The general AD cohorts included 7472–10 375 patients and the DS-AD subcohorts included 31–45 patients.

PRIMARY OUTCOME MEASURES: Demographics, comorbidities, co-medications and healthcare resource utilisation present up to and including the date of cohort qualification were described.

RESULTS

The mean age at index was 81–83 years in the general AD cohorts (median: 82–84 years), while in the DS-AD subcohorts, mean age ranged from 55 to 56 years (median: 56–57 years). Most patients in the general AD cohorts and the DS-AD subcohorts were white (87–94%). When descriptively compared with the general AD cohorts, a higher proportion of patients in the DS-AD subcohorts had asthma and chronic obstructive pulmonary disease (71–76% vs 60–63%), thyroid disease (38–42% vs 15–16%), hearing loss (29–31% vs 21–24%) and epilepsy (23–31% vs 2–3%). When descriptively compared with the general AD cohorts, a higher proportion of patients in the DS-AD subcohorts used thyroid therapy (44–45% vs 14–15%), topical and systemic antipsoriatics (16–22% vs 8%) and anti-epileptics (16–20% vs 6–7%).

CONCLUSIONS

In England, individuals with DS were typically diagnosed with AD at younger ages (50s) than those from the general population (80s). Higher frequencies of asthma, thyroid disease, hearing loss and epilepsy in the DS-AD subcohorts than the general AD cohorts align with known DS comorbidities. Therefore, some of the observed differences may be partly attributable to the underlying characteristics of DS, rather than representing a distinct AD phenotype among individuals with DS. Exploratory differences between cohorts should be interpreted in view of the substantial age gap and modest DS-AD sample size. This study provides novel insights into the real-world population of individuals with DS who were newly diagnosed with AD and may help clinicians to better tailor patient care.