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Table 1 Properties of QOL scales used for longitudinal and cross-sectional comparison

From: A brief guide to the selection of quality of life instrument

Likely to be a good Longitudinal questionnaire

Likely to be a good Cross-sectional questionnaire

Short (typically 1 – 40 items)

Long (typically 20 – 100 items)

Multi-response (e.g., 7-response) format item

Simple (e.g., binary or tertiary) response format

Limited severity range: Items describe problems common to most patients, or only in the population to be studied

Items cover the whole severity range of QOL deficit

No items showing floor or ceiling effects (i.e., items where >70% respond at either end of the scale) within target population

Items with floor and ceiling effects should be included

Items must be relevant to most patients

Items need not be relevant to all patients

Items irrelevant to the disease should not be included (unless the scale is used to test for iatrogenic change)

Items irrelevant to the disease should not be included (unless the scale is to be sensitive to co-morbidity)