title: Prevalence of below-criterion Reliable Digit Span scores in a clinical sample of older adults.
abstract: OBJECTIVE
  The Reliable Digit Span (RDS) is a well-validated embedded indicator of performance validity. An RDS score of ≤7 is commonly referenced as indicative of invalid performance; however, few studies have examined the classification accuracy of the RDS among individuals suspected for dementia. The current study evaluated performance of the RDS in a clinical sample of 934 non-litigating individuals presenting to an outpatient memory disorders clinic for assessment of dementia.
  
  
  METHODS
  The RDS was calculated for each participant in the context of a comprehensive neuropsychological assessment completed as part of routine clinical care. Score distributions were examined to establish the base rate of below criterion performance for RDS cutoffs of ≤7, ≤6, and ≤5. One-way ANOVA was used to compare performance on a cognitive screening measure and informant reports of functional independence of those falling below and above cutoffs.
  
  
  RESULTS
  A cutoff score of ≤7 resulted in a high prevalence of below-criterion performance (29.7%), though an RDS of ≤6 was associated with fewer below-criterion scores (12.8%) and prevalence of an RDS of ≤5 was infrequent (4.3%). Those scoring below cutoffs performed worse on cognitive measures compared with those falling above cutoffs.
  
  
  CONCLUSIONS
  Using the RDS as a measure of performance validity among individuals presenting with a possibility of dementia increases the risk of misinterpreting genuine cognitive impairment as invalid performance when higher cutoffs are used; lower cutoffs may be useful when interpreted in conjunction with other measures of performance validity.
authors.affiliation: Department of Psychology, University of Nevada, Las Vegas, Las Vegas, NV, USA.
authors.forename: RyAnna
authors.initials: R
authors.lastname: Zenisek
authors.affiliation: Department of Physical Medicine and Rehabilitation, Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Scott R
authors.initials: SR
authors.lastname: Millis
authors.affiliation: Cleveland Clinic Lou Ruvo Center for Brain Health, Las Vegas, NV, USA.
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Banks
authors.affiliation: Cleveland Clinic Lou Ruvo Center for Brain Health, Las Vegas, NV, USA millerj4@ccf.org.
authors.forename: Justin B
authors.initials: JB
authors.lastname: Miller
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D005260:Female; D015577:Geriatric Assessment; D006801:Humans; D008297:Male; D008306:Malingering / Q000175:diagnosis* / Q000453:epidemiology*; D008569:Memory Disorders / Q000175:diagnosis* / Q000453:epidemiology; D008570:Memory, Short-Term / Q000502:physiology*; D008875:Middle Aged; D009483:Neuropsychological Tests; D015203:Reproducibility of Results
keywords: Assessment; Dementia; Malingering/symptom validity testing; Reliable Digit Span