Attrition and bias in the MRC cognitive function and ageing study: an epidemiological investigation

Matthews, Fiona E.; Chatfield, Mark; Freeman, Carol; McCracken, Cherie; Brayne, Carol
January 2004
BMC Public Health;2004, Vol. 4, p12
Academic Journal
Background: Any hypothesis in longitudinal studies may be affected by attrition and poor response rates. The MRC Cognitive Function and Ageing study (MRC CFAS) is a population based longitudinal study in five centres with identical methodology in England and Wales each recruiting approximately 2,500 individuals. This paper aims to identify potential biases in the two-year follow-up interviews. Methods: Initial non-response: Those not in the baseline interviews were compared in terms of mortality to those who were in the baseline interviews at the time of the second wave interviews (1993-1996). Longitudinal attrition: Logistic regression analysis was used to examine baseline differences between individuals who took part in the two-year longitudinal wave compared with those who did not. Results: Initial non-response: Individuals who moved away after sampling but before baseline interview were 1.8 times more likely to die by two years (95% Confidence interval(CI) 1.3-2.4) compared to respondents, after adjusting for age. The refusers had a slightly higher, but similar mortality pattern to responders (Odds ratio 1.2, 95%CI 1.1-1.4). Longitudinal attrition: Predictors for drop out due to death were being older, male, having impaired activities of daily living, poor self-perceived health, poor cognitive ability and smoking. Similarly individuals who refused were more likely to have poor cognitive ability, but had less years of full-time education and were more often living in their own home though less likely to be living alone. There was a higher refusal rate in the rural centres. Individuals who moved away or were uncontactable were more likely to be single, smokers, demented or depressed and were less likely to have moved if in warden-controlled accommodation at baseline. Conclusions: Longitudinal estimation of factors mentioned above could be biased, particularly cognitive ability and estimates of movements from own home to residential homes. However, these differences could also affect other investigations, particularly the estimates of incidence and longitudinal effects of health and psychiatric diseases, where the factors shown here to be associated with attrition are risk factors for the diseases. All longitudinal studies should investigate attrition and this may help with aspects of design and with the analysis of specific hypotheses.


Related Articles

  • A comparison of parametric models for the investigation of the shape of cognitive change in the older population. Terrera, Graciela Muniz; Matthews, Fiona; Brayne, Carol // BMC Neurology;2008, Vol. 8, Special section p1 

    Background: Cognitive decline is a major threat to well being in later life. Change scores and regression based models have often been used for its investigation. Most methods used to describe cognitive decline assume individuals lose their cognitive abilities at a constant rate with time. The...

  • EFFECTS OF ATTRITION ON ESTIMATES OF CHANGE IN COGNITIVE ABILITIES. Kasl-Godley, J. E.; Pedersen, N. L.; Berg, S.; Gatz, M. // Gerontologist;Oct1996 Supplement, Vol. 36 Issue 1, p285 

    Attrition in longitudinal studies can affect the accuracy of conclusions about cognitive change. The present study tested whether observed scores on cognitive tasks were different from those which would have been obtained had attrition not occurred Subjects were non-demented individuals, age 50...

  • Predictors impaired cognitive function in men over the age of 80 years: results from the Health in Men Study. Flicker, Leon; Almeida, Osvaldo P.; Acres, John; Le, Max T. Q.; Tuohy, Raywin J.; Jamrozik, Konrad; Hankey, Graeme; Norman, Paul // Age & Ageing;Jan2005, Vol. 34 Issue 1, p77 

    Focuses on a study which analyzed the predictors of impaired cognitive function in older men. Factors and conditions that may be directly detrimental to cognitive function or may precipitate cognitive decline in vulnerable individuals; Hazard ratios for the presence of cognitive impairment at...

  • Does the optimal BMI really vary by age and sex? Xu, L.; Yeung, S. L. Au; Schooling, C. Mary; Sang-Wook Yi; Heechoul Ohrr; Jee-Jeon YI; Au Yeung, S L // International Journal of Epidemiology;Feb2016, Vol. 45 Issue 1, p285 

    No abstract available.

  • Midlife Risk Factors for Impaired Physical and Cognitive Functioning at Older Ages: A Cohort Study. Brunner, Eric J.; Welch, Catherine A.; Shipley, Martin J.; Ahmadi-Abhari, Sara; Singh-Manoux, Archana; Kivimäki, Mika // Journals of Gerontology Series A: Biological Sciences & Medical ;Feb2017, Vol. 72 Issue 2, p237 

    Background: Previous studies examined midlife risk factors separately for old-age impaired physical and cognitive functioning. We determined the overlap of risk factors for both domains of functioning within the same setting.Methods: Biological and behavioral risk...

  • Sociodemographic risk factors of the occurrence of cognitive impairments and the methods of cognitive impairment's assessment among diabetic patients. Derkacz, Marek; Chmiel-Perzyńska, Iwona; Marczewski, Krzysztof // Experimental & Clinical Diabetology / Diabetologia Doswiadczalna;2010, Vol. 10 Issue 2, p91 

    Background. The aim of the study was the attempt of finding the simple screening tests assessing the cognitive functions of patients with diabetes and determination of risk factors of the occurrence of cognitive impairments among diabetic patients. Material and methods. 122 diabetic patients...

  • YaÅŸlanan dünyanın hastalığı: Alzheimer hastalığı. Özkay, Ümide Demir; Öztürk, Yusuf; Can, Özgür Devrim // Medical Journal of Suleyman Demirel University;Mar2011, Vol. 18 Issue 1, p35 

    Alzheimer's disease (AD) is a progressive neurodegenerative disease which is characterized by decreases in cognitive functions and abilities of daily life activities, behavioral changes and psychiatric symptoms. The prevalence of AD, causing significant decrease in patient's life quality and...

  • GABAA Receptor-Mediated Acceleration of Aging- Associated Memory Decline in APP/PS1 Mice and Its Pharmacological Treatment by Picrotoxin. Yoshiike, Yuji; Kimura, Tetsuya; Yamashita, Shunji; Furudate, Hiroyuki; Mizoroki, Tatsuya; Murayama, Miyuki; Takashima, Akihiko // PLoS ONE;2008, Vol. 3 Issue 8, p1 

    Advanced age and mutations in the genes encoding amyloid precursor protein (APP) and presenilin (PS1) are two serious risk factors for Alzheimer's disease (AD). Finding common pathogenic changes originating from these risks may lead to a new therapeutic strategy. We observed a decline in memory...

  • Cardiovascular factors moderate the association of infection burden with cognitive function in young to middle-aged U.S. adults. Hedges, Dawson W.; Berrett, Andrew N.; Erickson, Lance D.; Brown, Bruce L.; Thacker, Evan L.; Gale, Shawn D. // PLoS ONE;6/13/2019, Vol. 14 Issue 6, p1 

    Background: Infectious diseases might affect cognitive aging and dementia risk, possibly via neuroinflammation. Similarly, risk factors for cardiovascular and cerebrovascular diseases are associated with cognitive function and dementia. We hypothesized that cardiovascular risk factors moderate...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics