Reference Identification

The validity and reproducibility of a work productivity and activity impairment instrument.

Pharmacoeconomics, Reilly MCReilly MC, Zbrozek AS, Dukes EM. dis 1993; 4:353-365
Country: USA
Language: English
https://www.ncbi.nlm.nih.gov/pubmed/10146874

Other references of interest

https://www.ncbi.nlm.nih.gov/pubmed/20860837

Validity of the work productivity and activity impairment questionnaire - general health version in patients with rheumatoid arthritis.

Instrument/Tool Translations References

Linguistic validation into 20 languages and content validity of the rheumatoid arthritis-specific Work Productivity and Activity Impairment questionnaire. 

https://pubmed.ncbi.nlm.nih.gov/24671921/