How quality of life is measured in studies of nutritional intervention: a systematic review

Nutrition care can positively affect multiple aspects of patient's health; outcomes are commonly evaluated on the basis of their impact on a patient's (i) illness-specific conditions and (ii) health-related quality of life (HRQoL). Our systematic review examined how HRQoL was measured in studies of nutritional interventions. To help future researchers select appropriate Quality of Life Questionnaires (QoLQ), we identified commonly-used instruments and their uses across populations in different regions, of different ages, and with different diseases.

We searched EMCare, EMBASE, and Medline databases for studies that had HRQoL and nutrition intervention terms in the title, the abstract, or the MeSH term classifications "quality of life" and any of "nutrition therapy", "diet therapy", or "dietary supplements" and identified 1,113 studies for possible inclusion.We then reviewed titles, abstracts, and full texts to identify studies for final inclusion.

Our review of titles, abstracts, and full texts resulted in the inclusion of 116 relevant studies in our final analysis. Our review identified 14 general and 25 disease-specific QoLQ. The most-used general QoLQ were the Short-Form 36-Item Health Survey (SF-36) in 27 studies and EuroQol 5-Dimension, (EQ-5D) in 26 studies. The European Organization for Research and Treatment of Cancer Quality of life Questionnaire (EORTC-QLQ), a cancer-specific QoLQ, was the most frequently used disease-specific QoLQ (28 studies). Disease-specific QoLQ were also identified for nutrition-related diseases such as diabetes, obesity, and dysphagia. Sixteen studies used multiple QoLQ, of which eight studies included both general and disease-specific measures of HRQoL. The most studied diseases were cancer (36 studies) and malnutrition (24 studies). There were few studies focused on specific age-group populations, with only 38 studies (33%) focused on adults 65 years and older and only 4 studies focused on pediatric patients. Regional variation in QoLQ use was observed, with EQ-5D used more frequently in Europe and SF-36 more commonly used in North America.

Use of QoLQ to measure HRQoL is well established in the literature; both general and disease-specific instruments are now available for use. We advise further studies to examine potential benefits of using both general and disease-specific QoLQ to better understand the impact of nutritional interventions on HRQoL.