Effects of age and cognitive function on data quality of standardized surveys in nursing home populations

Data quality is of special concern when it comes to survey research in nursing homes. Very little is known about specifics of cognitively impaired elderly in responding to survey questions. This study examines effects of cognitive impairment, age, gender, and interview duration on the data quality in a sample of 659 nursing home residents (NHR).

Within a cross-sectional design, survey methodology was used to evaluate the pain situation in 13 nursing homes. Residents were stratified into NHR with no/mild (Mini-Mental State Examination MMSE: 18-30) and NHR with moderate (MMSE: 10-17) cognitive impairment. Data quality is measured by item nonresponse (INR). Correlation analyses, ANCOVA, linear and logistic regression models are applied.

Neither interview duration nor gender have effects on item nonresponse. Age accounts for higher INR (β = 0.12, p < 0.001). Cognitive impairment strongly predicts INR (β = - 0.40, p < 0.001). INR significantly differs between NHR with no/mild (3.98%) and moderate cognitive impairment (11.85%). The likelihood of INR > 5% for residents with moderate cognitive impairment is 3.8-times (p < 0.001) of that for those with no/mild impairment.

Surveys are adequate for residents with no/mild cognitive impairment but data quality is threatened in residents with moderate impairments. Precision and validity of responses from NHR with progressed cognitive impairment are potentially limited and results may be biased. The results clearly do support the need for a multidisciplinary 'general theory' of the question-/answer-process which has to be also inclusive for cognitively impaired elderly persons.