Devising a Missing Data Rule for a Quality of Life Questionnaire-A Simulation Study.
Peter Jacoby, Andrew Whitehouse, Helen Leonard and 4 others
PMID 35075044WHAT IT FOUND
For the QI-Disability questionnaire, imputing missing items with the mean of completed items is accurate for Positive Emotions and Social Interaction if one item is missing.
For other domains, scores should not be calculated if any item is missing. A total score is valid if no domain has more than one missing item.
Key findings
01A total QI-Disability score can be calculated if there is no more than one missing item per domain.
02Positive Emotions and Social Interaction domain scores can be imputed if there is one missing item.
03Other domain scores should not be calculated if there is one or more missing item.
STILL TO COME
How it was doneWhat they foundWhat it means for OTs
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What it does not show
The simulation assumed items were missing completely at random (MCAR). If items are missing for reasons related to the patient's condition (e.g., a specific domain is skipped because of communication difficulties), the results may not apply. The study used a specific dataset of children with intellectual disabilities. The rules may not transfer directly to other populations or other quality of life measures.
Declared interests
The research was supported by the NIH (Extramural) and non-US government sources. No commercial conflicts of interest are reported in the provided text.
The easy way to misread this
Do not assume that averaging the remaining items is always safe for all domains. The study shows that for Physical Health, Negative Emotions, Leisure, and Independence, even a single missing item makes the imputed score unreliable according to strict measurement error standards.