Risk of dementia and visual impairment in the Chinese elderly

Study design, setting and samples

This 6-year longitudinal observational study is based on an area-wide community cohort of the Elderly Health Center (EHC), Department of Health, Hong Kong Government, reported elsewhere.⁸Briefly, our cohort consisted of 18,298 people aged 65 and over from all 18 districts of Hong Kong at the start. All participants underwent a standardized clinical assessment of cognitive status and a comprehensive assessment of a wide range of physical and mental health problems, lifestyle behaviors, and sociodemographic factors in her EHC at baseline. Has completed. Since then they have been tracked annually in her EHC. In this study, those who missed follow-up were actively tracked and interviewed, and prior to interview, written consent was obtained from all participants in the study or from their legal representatives if they were mentally unable to give consent. informed consent was obtained. The names of those who could not be traced were confirmed on death registers for cause of death.

This study was approved by the Ethics Committee of the Government and the Institutional Review Board of the University. This research was conducted in accordance with the principles of the Declaration of Helsinki.

This study aimed to examine the association between baseline dementia and 6-year visual impairment in Chinese, not Chinese (n = 60), but with baseline visual impairment (n = 6367). , excluded participants who developed dementia. at follow-up (n = 1065). Therefore, a total of 10,806 participants without visual impairment at baseline were included.

Visual impairment identification

Visual acuity was assessed annually for both eyes using the line score of a 6-m Snellen E-chart mounted on the EHC wall. Accounting for non-normal distributions, Snellen fractions were transformed to LogMAR, with higher scores indicating worse visual acuity. In this study, visual impairment was defined as a better eye with visual acuity of 6/18 (or LogMAR ≥ 0.5) or less despite best correction.Health Authority (WHO) definition⁹The result of the study was 6 years of occasional visual impairment.

Identifying dementia

To reduce the potential risk of misclassifying visually impaired participants as dementia due to poor performance on vision-dependent cognitive tasks, we performed a comprehensive clinical examination. This included significant memory decline or executive dysfunction rather than sensory deficits, and non-visual cognitive tests such as the delayed word recall test and the abbreviated mental test at his EHC at baseline. As a means of minimizing the risk of reverse causation, participants found to have developed dementia were excluded from data analyses, so the same tests were repeated on her EHC at follow-up. Participants who missed this but agreed to a follow-up interview at home at EHC or follow-up underwent clinical examination and a clinical dementia assessment by a geriatric psychiatrist. Dementia was diagnosed according to the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) and the Clinical Dementia Rating (CDR) of 1-3.¹⁹A panel of geriatric psychiatrists independently reviewed all diagnoses of dementia. In cases where the diagnosis was equivocal or inconsistent, the attending physician made the final diagnosis.

Evaluation of other variables

Information on sociodemographic factors, clinical risk factors, hearing and disability, and lifestyle behaviors was obtained during the evaluation. Demographic factors include age, gender, and level of education. Low socioeconomic status was defined as receiving Comprehensive Social Security Assistance (CSSA) from the government. Clinical risk factors include cataracts, glaucoma, diabetes, hypertension, hypercholesterolemia, heart disease, stroke, Parkinson’s disease and depression. They were diagnosed with reference to ICD-10 criteria by ophthalmologists, physicians and psychiatrists accordingly. Hearing impairment was defined as loss of 1 and 2 kHz >40 dB in the better ear during audiometry (Audioscope, Welch Allyn 23300). Disability was defined as needing assistance with walking or being confined to a chair. A standardized self-report questionnaire was used to assess participants’ lifestyle behaviors over the previous month.Various lifestyle behavior classification systems have already been validated for Chinese seniors in Hong Kong²⁰Criteria for regular participation in physical, intellectual, and social activities, consumption of adequate amounts of fruits and vegetables, and smoking were defined as previously reported.^{twenty one,twenty three,twenty three}.

statistical analysis

Sample size estimation was performed using G*Power software.Sample size was calculated based on estimates of annual decline in visual acuity (~0.01 LogMAR per year) and correlation with MMSE change from previous longitudinal studies¹² Mean and standard deviation of point prevalence of dementia and visual acuity in participants at baseline from previous studies⁸Because older adults with dementia had lower MMSE scores and a greater rate of decline than those without dementia, the proportion of participants who developed visual impairment over 6 years was higher in the dementia group than in the dementia-free group. I estimated it to be about 50% bigger. With alpha set to 0.05, a sample of 4,000 participants must be at least 80% to detect a significant difference in her 6-year incidence of visual impairment between those with and without dementia at baseline. gives a power of .

Statistical analysis was performed using IBM SPSS Statistics, version 26.0 (IBM Corp). Incidence of visual impairment (ie, events) was calculated based on the number of participants who developed visual impairment over a 6-year period. A Kaplan-Meier curve was constructed to show 6-year survival without visual impairment. Data were censored if participants remained visually impaired by the end of the study, failed to follow up, or died without visual impairment before the study was terminated.

Baseline dementia and other variables were compared between independent participants with and without visual impairment. t– test or X² Test as needed.The level of statistical significance is P.< 0.05 (both sides).

Cox regression analysis was performed to examine the effect of dementia (and other variables) on time to visual impairment at baseline. In our analysis, the primary outcome was the development of visual impairment and the predictor variable was the presence of dementia at baseline. Hazard ratios (HR) were calculated to provide point estimates with 95% confidence intervals (95% CI) and plotted the difference in his 6-year visual impairment-free survival associated with the presence of baseline dementia Did. To control for potential confounding effects, multivariate analyzes were performed to compare baseline visual acuity and each covariate (cataract, glaucoma, diabetes, hypertension, hypercholesterolemia, heart disease, stroke, Parkinson’s disease, depression, hearing) were included to calculate the adjusted HR. disability, physical disability, participation in physical exertion, intellectual and social activity, adequate daily intake of fruits and vegetables, smoking, age, female sex, level of education, and low socioeconomic status). add.

ethical approval

This study was approved by the Ethics Committee of the Ministry of Health, Government of Hong Kong (L/M 623/2010) and the Joint Clinical Research Ethics Committee of the New Territories East Cluster of The Chinese University of Hong Kong and Hospitals. Permissions (CRE-2011.036).