How do I design a study with QoL?

There are 4 main steps to consider for the design of a QoL study:

  1. Determine your QOL Objective
    • Write down the specific question you want to answer. Take extra care to determine which specific QoL domains, what time periods and what type of changes/differences you are expecting to be relevant for your question.
  2. Choose an instrument
    • It should be a validated (i.e. reliable, valid, responsive, feasible ?) questionnaire in the trial population.
    • It should address the QoL domains that are essential for your hypothesis: global measures, disease-specific measures,and symptom checklists.
    • Check if appropriate translations are available.
  3. Select your assessment time points
    • Assessment schedule should closely reflect the objective.
    • Schedule should include at least a baseline (i.e. before treatment/randomization).
    • If comparing multiple arms: schedule should be identical/comparable between the arms.
    • Keep the patient in mind: do not overburden by collecting more than necessary.
  4. Develop an analysis plan
    • Analysis plan should reflect the objective.
    • Address issues of scale/domain selection, sample size, compliance, missing data, minimal clinically important difference and sensitivity analyses.

Note that objectives, instrument, assessment schedule and analysis techniques should be specified a priori. A good trial design, conduct, analysis and reporting is only possible if these aspects have been determined beforehand.

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