HAQ

Health Assessment Questionnaire (HAQ) is a standardized patient-reported outcome (PRO) instrument designed to quantify functional disability—originally in rheumatoid arthritis, but now widely used across rheumatologic and systemic inflammatory diseases (including myositis) to capture what patients can actually do in daily life. The classic version is the HAQ Disability Index (HAQ-DI), a 0–3 scale where higher scores indicate worse function. It is fast, highly validated, sensitive to change in many inflammatory conditions, and frequently used in clinical trials and routine care as a global measure of physical function. [1–3]

What HAQ measures

HAQ-DI focuses on the patient’s difficulty performing activities of daily living (ADLs) over the prior week (some versions use 1–2 weeks). It covers 8 functional domains, each containing 2–3 questions:

1. Dressing & grooming
2. Arising (standing up, getting in/out of bed/chair)
3. Eating
4. Walking
5. Hygiene (bathing, toileting)
6. Reach (e.g., reaching overhead)
7. Grip (e.g., opening jars)
8. Common activities (e.g., chores, errands)

Each item is scored 0 to 3:

• 0 = no difficulty
• 1 = some difficulty
• 2 = much difficulty
• 3 = unable to do

How HAQ-DI is calculated

For each domain, you take the highest item score within that domain (not the average). Then the HAQ-DI is the mean of the 8 domain scores, producing a final value from 0.00 to 3.00. [1,2]

Aids/devices and assistance (important nuance): The HAQ includes questions about whether the patient uses assistive devices (cane, walker, special utensils, raised toilet seat, etc.) or needs help from another person. In the traditional scoring approach, if a device or assistance is required for a domain, the domain score is raised to at least 2(even if the raw difficulty items are lower), because reliance on aids/assistance indicates clinically meaningful disability. Some modern implementations report both “raw” and “adjusted” scores, but the classic HAQ-DI uses this adjustment. [1,2]

How to interpret HAQ-DI

• 0.0–1.0: mild disability
• 1.0–2.0: moderate disability
• 2.0–3.0: severe disability

These cutoffs are not absolute rules, but they are commonly used heuristics in rheumatology and outcomes research. HAQ-DI is strongly associated with work disability, healthcare utilization, and long-term outcomes in inflammatory disease populations. [2,3]

What constitutes a meaningful change

In many rheumatologic conditions, a change of about 0.22–0.25 in HAQ-DI is often cited as a minimal clinically important difference (MCID), though the MCID varies by disease, baseline severity, and context (trial vs routine practice). [3] In myositis trials, HAQ-DI may be used as part of broader response sets or as a supportive functional endpoint, but it is not as myositis-specific as instruments like the Health Assessment Questionnaire for Myositis (HAQ-M) or myositis activity measures.

Related instruments you may see

• mHAQ (Modified HAQ): shorter, less granular; can be easier in clinic but may be less sensitive.
• HAQ-II: revised item set and scoring; intended to improve psychometrics in some populations.
• MDHAQ: multidimensional HAQ used in many clinics (adds pain, global, fatigue, etc.).
• HAQ-M: adapted for myositis functional limitations (used in some myositis studies).

If you tell me whether you mean HAQ-DI, MDHAQ, or HAQ-M, I can tailor the description to the exact instrument you’re using.

References (AMA)

1. Fries JF, Spitz P, Kraines RG, Holman HR. Measurement of patient outcome in arthritis. Arthritis Rheum.1980;23(2):137-145. doi:10.1002/art.1780230202.
2. Bruce B, Fries JF. The Health Assessment Questionnaire (HAQ). Clin Exp Rheumatol. 2005;23(5 Suppl 39):S14-S18.
3. Pope JE, Khanna D, Norrie D, Ouimet JM. The minimally important difference for the Health Assessment Questionnaire in rheumatoid arthritis and other rheumatic diseases: a systematic review. J Rheumatol.2009;36(9):1834-1840. doi:10.3899/jrheum.090087.