Questionnaires in Drug Evaluation

Questionnaires in Drug Evaluation

1. Definition, scope & role in drug evaluation

• A questionnaire (more broadly a self-reported measure) is an instrument in which participants describe their own behaviours, attitudes, medical history, symptoms, functioning, or quality of life — as distinct from data measured objectively by an observer, device, or assay (Browner DCR 5e Ch.17, p.2).
• Self-reported data may be gathered as paper-based or online questionnaires, paper or electronic diaries/logs, and structured interviews conducted in person or by telephone; regardless of mode, good self-reported measures share the same design principles — clear instructions and well-phrased questions that elicit informative responses, tailored to the target population's literacy level and cultural assumptions (Browner DCR 5e Ch.17, p.2).
• Why questionnaires matter in drug evaluation: for many clinical-trial endpoints the validity of the study's findings depends on how well the self-reported information is ascertained — i.e. the questionnaire is the measurement instrument for the endpoint, and a poorly-designed instrument biases the efficacy/safety read-out (Browner DCR 5e Ch.17, p.2; summary point 1, p.26).
• Subjective outcomes that questionnaires uniquely capture in drug trials:
  • Symptoms and their frequency/severity/intensity (e.g. pain severity in the past 7 days) (Browner DCR 5e Ch.17, pp.4–5).
  • Health-related quality of life (HRQoL) and functioning — abstract constructs that need multi-item scaling (Browner DCR 5e Ch.17, pp.2–3, p.10).
  • Treatment satisfaction (e.g. satisfaction with control of pain) (Browner DCR 5e Ch.17, p.5).
  • Medication adherence — self-reported recall of whether prescribed medicines were taken (Browner DCR 5e Ch.17, pp.7–8).
  • Adverse drug reactions / patient-reported tolerability — symptom-based ADRs (nausea, dizziness, sexual dysfunction) that are defined primarily by the patient's perception (Browner DCR 5e Ch.17, pp.7, 26).
• Irreplaceable role: some conditions and treatment effects are defined primarily by the patient's perception of symptoms — e.g. generalized anxiety disorder, irritable bowel syndrome, insomnia (sleep quality, daytime sleepiness) — for which self-reported instruments are "the best, if not the only, measure" of the participant's experience; physiologic surrogates (actigraphy, accelerometry) cannot replace them (Browner DCR 5e Ch.17, p.26).
• Patient-reported outcome (PRO): in the regulatory framing, a PRO is any report of the status of a patient's health condition that comes directly from the patient, without interpretation of the patient's response by a clinician or anyone else; the FDA reviews PRO instruments used to support claims in approved drug labeling (FDA PRO Guidance, Dec 2009) [FDA].
• Scope boundary (this topic): the focus is the measurement instrument — designing, selecting, administering, and validating questionnaires that quantify subjective endpoints in drug evaluation — NOT the overall study design (RCT/cohort) or objective endpoints (laboratory, imaging, hard clinical events), which are separate topics (Browner DCR 5e Ch.17, p.2; scope note).