title: Construct validity of the Work Productivity and Activity Impairment questionnaire across informal caregivers of chronically ill older patients.
abstract: OBJECTIVE
  To assess the validity of the Work Productivity and Activity Impairment questionnaire as adapted for caregiving (WPAI:CG) to measure productivity loss (hours missed from work, impairment while at work, and impairment in regular activities) due to unpaid caregiving for medically complex older adults.
  
  
  METHODS
  The WPAI:CG was administered along with the Caregiver Strain Index (CSI) and Center for Epidemiologic Studies Depression Scale (CESD) to a caregiving population (N = 308) enrolled with their older, medically complex care-recipient in a cluster-randomized controlled study. Correlation coefficients were calculated between each productivity variable derived from the WPAI:CG and CSI/CESD scores. Nonparametric tests for trend across ordered groups were carried out to examine the relationship between each productivity variable and the intensity of the caregiving.
  
  
  RESULTS
  Significant positive correlations were found between work productivity loss and caregiving-related strain (r = 0.45) and depression (r = 0.30). Measures of productivity loss were also highly associated with caregiving intensity (P < 0.05) and care-recipient medical care use (P < 0.05). The average employed caregiver reported 1.5 hours absence from work in the previous week and 18.5% reduced productivity while at work due to caregiving. Employed and nonemployed caregivers reported 27.2% reduced productivity in regular activities in the previous week.
  
  
  CONCLUSIONS
  The results indicate high convergent validity of the WPAI:CG questionnaire. This measure could facilitate research on the cost-effectiveness of caregiver-workplace interventions and provide employers and policy experts with a more accurate and comprehensive estimate of caregiving-related costs incurred by employers and society.
authors.affiliation: Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.
authors.forename: Erin R
authors.initials: ER
authors.lastname: Giovannetti
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Wolff
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Frick
authors.forename: Chad
authors.initials: C
authors.lastname: Boult
mesh_terms: D000041:Absenteeism; D000203:Activities of Daily Living; D000368:Aged; D017028:Caregivers / Q000523:psychology* / Q000706:statistics & numerical data; D002908:Chronic Disease / Q000523:psychology; D003866:Depressive Disorder / Q000209:etiology / Q000523:psychology; D004219:District of Columbia; D004526:Efficiency; D005260:Female; D006801:Humans; D008297:Male; D008396:Maryland; D008875:Middle Aged; D011788:Quality of Life; D016032:Randomized Controlled Trials as Topic; D018434:Sickness Impact Profile; D013315:Stress, Psychological / Q000209:etiology; D011795:Surveys and Questionnaires / Q000592:standards*; D017132:Workplace / Q000523:psychology*