Persons with an affirmative response in JNTYR were asked follow-up questions on whether they had experienced joint symptoms on most days for at least a month (JNTDAILY1MO) and whether their symptoms had begun because of an injury (JNTINJURY).

Persons who answered "Yes" to the question associated with JNTYR were also handed a card showing a figure of the body (front and back) with sixteen joints labeled and numbered. They were then asked the follow-up question, "Which joints are affected?" Responses to this question were converted into dichotomous variables by the National Center for Health Statistics, with each variable indicating whether the joint was "Mentioned" or "Not mentioned" as being affected. See JNTYRANKLEL for a list of the variables for affected joints.

In 1999 only, those with an affirmative response in JNTYR were asked whether they had taken steroid medication during the past 12 months (JNTSTEROIDYR) and whether the following specific conditions had been diagnosed by a doctor as the cause of their joint problems:

• Rheumatoid arthritis (JNTRHEUMARTH)

• Osteo- or degenerative arthritis (JNTOSTEOARTH)

• Other arthritis (JNTOTHARTH)

• Gout (JNTGOUT)

• Bursitis or tendinitis (JNTBURSITIS)

• Other condition (JNTOTHCAUSE)

Beginning in 2002, sample adults age 18+ were asked whether they had "any symptoms of pain, aching, or stiffness in or around a joint" during the past 30 days, excluding the back or neck (JNTMO). As in 1997-2001, persons who reported having joint problems were asked a follow-up question about which joints were affected (see JNTMOANKLEL for a list of the affected joint variables available for 2002 forward).

Because of the change in the reference period (past 12 months in 1997-2001 versus past 30 days in 2002 forward) and the change in question wording (i.e., back and neck problems were excluded beginning in 2002), the NHIS Survey Descriptions for 2003 forward warn that any comparisons of joint symptom data between the two time periods "should be undertaken with caution."