Assessing statistical applications in publications on Alzheimer's disease

Dietary patterns and risk of mild cognitive impairment among Chinese elderly: A cross-sectional study

Objective

To investigate the relationship between food patterns and mild cognitive impairment (MCI) among Chinese elderly to provide evidence for risk prevention and control of MCI among elderly population.

Methods

Between February 2017 to October 2018, a stratified multistage cluster sampling method was used to select participants from 760 communities of six districts in Xi’an, China, for 49-item food frequency questionnaire survey. A total of 2311 participants aged 60 to 88 years were included in the study with 444 (19.2%) participants of MCI among Chinese community-dwelling elderly adults. Food patterns associated with risk of dementia were assessed by using a reduced rank regression (RRR) analysis, and the multivariate linear regression was used to test trends of risk factors across scores for the food pattern.

Results

Four dietary patterns were extracted which explained 88.65% of the total variation in food intakes. Furthermore, the food pattern 1 (FP1) accounted for 60.25% of the total variation of all responsible variables and as a target dietary pattern in the study, which was related with high intake of legumes, vegetables, fruits, milk and dairy products, nuts and a low intake of noodles and cereals (p<0.05). Multivariate linear regression analysis showed that participants with a high score for FP1 had higher direction, memory and language function and FP1 can improve the ability of cognitive function (p<0.05).

Conclusion

The FP1 of Chinese dietary patterns was significantly correlated with higher cognitive function which can reduce the risk of MCI among Chinese elderly.

Evaluating the quality of longitudinal statistical applications in original publications on Alzheimer's disease

BACKGROUND/AIMS

To evaluate the quality of longitudinal statistical applications in published studies on Alzheimer's disease (AD).

METHODS

A 21-item instrument, the Quality of Longitudinal AD Studies (QLADS), was developed by the research team (4 biostatisticians, 1 neuroepidemiologist, and 1 neurologist). All items were extensively discussed within the team for content validity. After pilot testing on 5 publications, the instrument was revised and tested for reliability with a sample of 40 published longitudinal AD studies randomly sampled from MEDLINE.

RESULTS

Item-specific test-retest reliability coefficients for QLADS ranged from 0.53 to 1.00 with the associated standard error (SE) ranging from 0.02 to 0.13. The test-retest reliability for the overall score over the 21 items was high (intraclass correlation coefficient (ICC) = 0.94, 95% CI 0.90, 0.97). Item-specific inter-rater reliability coefficients for QLADS ranged from 0.46 to 1.00 with the associated SE ranging from 0.07 to 0.18. The inter-rater reliability for the overall score was also high (ICC = 0.87, 95% CI 0.77, 0.93).

CONCLUSIONS

This study indicates that the quality of longitudinal statistical applications in AD publications can be reliably assessed.