Some asthma-related variables, such as ASTHMAEV, were included in the National Health Interview Survey (NHIS) every year, beginning in 1997. From 1997 forward, the NHIS included questions about whether, in the past 12 months, individuals had an asthma attack (ASTHATAKYR) and had visited an emergency room for asthma (ASTHERYR). Beginning in 2001, individuals ever diagnosed with asthma were consistently asked whether they still had asthma (ASTHMASTIL).

Most of the questions related to asthma were, however, only included in the survey periodically. The 1999 and 2003 surveys were particularly notable for the large number of asthma-related variables they included. According to the 2003 Manual, the new asthma questions for that year were "part of the Healthy People 2010 Initiative."

One group of the "periodic" asthma questions addressed the effects of the illness, in terms of the use of health care or disability days. Variables in this group included:

• Had hospital stay for asthma, past 12 months (ASTHOSPYR, in 1999, 2003, 2008, 2013)

• Number hospital stays for asthma, past 12 months (ASTHOSPYRNO, in 1999)

• Days missed due to asthma, past 12 months (ASTHDAYR, in 2002-2003, 2008, 2013)

A second group of periodically-available asthma questions dealt with the use of asthma medications. These included:

• Used over the counter meds for asthma, past 12 months (ASTHOTCYR, in 1999)

• Used prescription inhaler, past 3 months (ASTHPIN3MO, in 1999)

• Number canisters prescription inhalers used, past 3 months (ASTHCANSNO, in1999)

• Ever used prescription inhaler (ASTHPINEV, in 2003, 2008)

• Used prescription inhaler for quick relief, past 3 months (ASTHPINQUICK, in 2003, 2008, 2013)

• Used more than 3 cans prescription inhaler, past 3 months (ASTHCANGT3, in 2003, 2008, 2013)

• Ever taken preventive asthma meds (ASTHPREV, in 2002-2003, 2008)

• Now taking preventive asthma meds (ASTHPRENOW, in 2003, 2008, 2013)

The third group of periodically-available asthma-related questions covered "patient education," broadly defined. More specifically, these questions addressed whether an individual had received training from health professionals about managing asthma, about recognizing and effectively treating early warning signs of an asthma episode, and about changing their environment to minimize the risk of attacks. These variables included:

• Ever taken class on managing asthma (ASTHCLASS, in 1991, 1998, 1999, 2003, 2008, 2013)

• Talk with health professional about managing asthma (ASTHMANAGE, in 2003, 2008)

• Ever taught to recognize early signs of asthma episode (ASTHSIGNS, in 2003, 2008, 2013)

• Ever taught how to respond to asthma episode (ASTHRESPOND, in 2003, 2008, 2013)

• Ever taught to monitor peak flow for daily therapy (ASTHPEAK, in 2003, 2008, 2013)

• Shown how to use inhaler (ASTHINSHOW in 2003, 2008)

• Ever given an asthma management plan (ASTHPLAN, in 2002-2003, 2008, 2013)

• Ever advised to change environment for asthma (ASTHCHEN, in 2002-2003, 2008, 2013)

• Followed advice to change environment for asthma (ASTHCHENYES, in 2003, 2008)

Available in 1991 only, ASTHMAYR identifies sample persons who reported that they had asthma during the past 12 months.

In 2007, LUNGPROBYR indicates whether sample children were ever diagnosed by a doctor or other health professional as having lung or breathing problems, other than asthma.