title: Handling missing Mini-Mental State Examination (MMSE) values: Results from a cross-sectional long-term-care study.
abstract: BACKGROUND
  Missing values are commonly encountered on the Mini Mental State Examination (MMSE), particularly when administered to frail older people. This presents challenges for MMSE scoring in research settings. We sought to describe missingness in MMSEs administered in long-term-care facilities (LTCF) and to compare and contrast approaches to dealing with missing items.
  
  
  METHODS
  As part of the Care and Construction project in Nova Scotia, Canada, LTCF residents completed an MMSE. Different methods of dealing with missing values (e.g., use of raw scores, raw scores/number of items attempted, scale-level multiple imputation [MI], and blended approaches) are compared to item-level MI.
  
  
  RESULTS
  The MMSE was administered to 320 residents living in 23 LTCF. The sample was predominately female (73%), and 38% of participants were aged >85 years. At least one item was missing from 122 (38.2%) of the MMSEs. Data were not Missing Completely at Random (MCAR), χ2(1110) = 1,351, p < 0.001. Using raw scores for those missing <6 items in combination with scale-level MI resulted in the regression coefficients and standard errors closest to item-level MI.
  
  
  CONCLUSIONS
  Patterns of missing items often suggest systematic problems, such as trouble with manual dexterity, literacy, or visual impairment. While these observations may be relatively easy to take into account in clinical settings, non-random missingness presents challenges for research and must be considered in statistical analyses. We present suggestions for dealing with missing MMSE data based on the extent of missingness and the goal of analyses.
authors.affiliation: Geriatric Medicine Research Unit, Nova Scotia Health Authority and Dalhousie University, Canada; Department of Family Studies and Gerontology and the Nova Scotia Centre on Aging, Mount Saint Vincent University, Canada.
authors.forename: Judith
authors.initials: J
authors.lastname: Godin
authors.affiliation: Department of Family Studies and Gerontology and the Nova Scotia Centre on Aging, Mount Saint Vincent University, Canada.
authors.forename: Janice
authors.initials: J
authors.lastname: Keefe
authors.affiliation: Geriatric Medicine Research Unit, Nova Scotia Health Authority and Dalhousie University, Canada. Electronic address: mandrew@dal.ca.
authors.forename: Melissa K
authors.initials: MK
authors.lastname: Andrew
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003071:Cognition / Q000502:physiology*; D003430:Cross-Sectional Studies; D003625:Data Collection / Q000592:standards*; D003627:Data Interpretation, Statistical; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008134:Long-Term Care; D008297:Male; D008403:Mass Screening; D008609:Mental Status Schedule; D008875:Middle Aged; D009674:Nova Scotia; D015203:Reproducibility of Results; D055815:Young Adult
keywords: Care and construction project; Long-term care; MMSE; Missing data; Multiple imputation