BPYRS is a 2-digit numeric variable with no implied decimals.
0: Not in universe
1: Less than 2 years
98: 98+
99: Unknown
For sample persons aged 18 and older who worked last year at a civilian job and who had back pain every day for at least 1 week last year, BPYRS reports the total number of years in which the person has had an episode of back pain lasting a week or more.
This variable was included in the 1988 Occupational Health supplement.