Age-Specific Hospital Incidence Rates in Dementia

Abstract

A random sample (n = 101,104) was taken from total general hospital admissions to Scottish hospitals (1:25 fraction) during the period 1968–1977. Record linkage was used to connect general hospital and psychiatric hospital morbidity records (SMR 1 and SMR 4). Patients with a subsequent admission with dementia (principal diagnosis ICD 9 290) were identified from the general hospital sample on follow-up. Age-specific first-admission rates for dementia were calculated for the hospital population considered. First-admission rates ranged from 41.9 (per 100,000 person-years-at-risk, PYR) for male patients aged 60–64 years to 514.2 in the age band 80 years and over. The equivalent figures for female patients were 40.8 (per 100,000 PYR) and 723.1. Epidemiological research has shown an approximate doubling of prevalence rates every 5 years after the age of 60 years, and the age-banded hospital admission rates in the present study are consistent with this underlying pattern. Expected first-admission rates in dementia were calculated from admission rates in dementia and community prevalence reported in previous studies. Expected rates were contrasted with the rates observed in the present study. An estimated 6-7% of prevalent dementia cases and between 11 and 14% of ‘expected dementia admissions’ achieved a recorded main diagnosis of dementia, and proportions were stable across age bands in the case of both measures. The wide discrepancy between expected and observed admission rates suggests relative underreporting of dementia as a principal diagnosis in hospital statistics.

The Effects of Dementia in German Acute Care Hospitals

“…This share is comparable with results by Ryan [11] for Scottish hospitals. All in all 37.7% of the patients with dementia are admitted to an acute care hos pital because of a severe disease of the circulatory system (ICD-9 390-459), like stroke or heart attack.…”

“…The low prevalence rate of dementia in our sample may be seen as an indirect sign of a general underestimation of this diag nosis, which has already been described in the literature [10,11]. For many hospital patients the condition of dementia either passes undetected or, if recognized, is not given enough importance to be recorded as a (main) diag nosis [11]. Detected or not, demographic aging will in crease the prevalence of dementia within the general pop ulation and among patients in acute care hospitals within the next decades.…”

“…Different studies conclude that senile dementia is strongly age-related [28,33,34], Depending on the specific instruments to diagnose dementia, the prevalence rates of dementia among the oldest old is esti mated to be between 16 and 43% in Germany [28], With respect to this observation the low frequency of dementia among elderly hospital patients is remarkable. The low prevalence rate of dementia in our sample may be seen as an indirect sign of a general underestimation of this diag nosis, which has already been described in the literature [10,11]. For many hospital patients the condition of dementia either passes undetected or, if recognized, is not given enough importance to be recorded as a (main) diag nosis [11].…”

Dementia ascertainment using existing data in UK longitudinal and cohort studies: a systematic review of methodology

“…A validity rate of 84% is quoted from a previous work by the same author [27]. Russ et al [10] also note the likelihood that SMR datasets will miss some cases of dementia.…”

“… No 10 Russ et al [ 10 ] Geographical variation in dementia (Scottish sub-study only) Outcome Full d ISD Scotland data, death certificates, records for a nursing home medical practice ICD-9 & 10 codes for dementia from d SMR data and death certificates, and dementia status reported by a medical practice. Yes 16 Ryan [ 27 ] Hospital incidence rates in dementia Outcome Full d ISD Scotland data. ICD-8 & 9 codes for dementia.…”