Rasch analysis in the development of the NutriQoL® questionnaire, a specific health-related quality of life instrument for home enteral nutrition

Background

Home enteral nutrition (HEN) is a therapeutic method used in patients who are unable to ingest the required amounts of nutrients but retain a functional gastrointestinal tract. The objective of this study was to compose a specific questionnaire for measuring health-related quality of life (HRQoL) in HEN patients irrespective of their underlying condition and HEN route of administration.

Methods

Literature review, focus groups and semi-structured interviews were used to propose an initial version of the questionnaire which was answered by 165 participants. The responses were analyzed using the Rasch methodology. Firstly, the appropriateness of response options was assessed. Then, the differential item functioning (DIF) was evaluated. Finally, the item fit statistics, infit and outfit, were determined.

Results

Rasch analysis was performed on the responses given to the 43 items included in the initial questionnaire. Four items were excluded because more than 50% of respondents answered that the situation proposed did not apply to them. Seven items that showed overlapping and disordered categories were also removed. Pairwise DIF analysis were performed in subgroups defined by underlying disease and administration route. Eleven items presented DIF and were eliminated from the questionnaire. Finally, four items were deleted after analyzing the fit statistics, three of which did not fit the Rasch model and one did not belong to either of the dimensions. The final version of NutriQoL® includes 17 items.

Conclusions

NutriQoL® is a useful instrument to assess the HRQoL of HEN patients with any disease and any administration route.

Reliability and Responsiveness of NutriQoL® Questionnaire

INTRODUCTION

NutriQoL^® (Nestlé Health Science, Vevay, Switzerland) is a questionnaire developed to assess the health-related quality-of-life (HRQoL) of patients with home enteral nutrition (HEN) irrespective of their underlying condition and route of administration. The aim of this work is assessing the questionnaire's reliability and responsiveness to change.

METHODS

Two cohorts of patients with HEN and their primary caregivers were enrolled to assess reliability and responsiveness, respectively. All participants had to be 18 years of age or older, without mental deterioration (≤3 or 4 errors in the Pfeiffer's test) and with sufficient functional status (>40 points on Karnovsky's performance status scale). When the patients' ability to respond to the questionnaire was impaired due to underlying disease, their caregivers answered on their behalf. NutriQoL was administered in two and three visits to reliability and responsiveness cohorts, respectively. Test-retest reliability and internal consistency were assessed by the intra-class correlation coefficient (ICC) and the Cronbach's α, respectively. Responsiveness was evaluated by standardized effect size and standardized response mean between basal visit and third visit. Finally, the minimal clinically important difference (MCID) was estimated.

RESULTS

A total of 54 and 86 participants were recruited to the reliability and responsiveness cohort, respectively. Thirty-five caregivers were selected to assess the inter-observer reliability. ICC values confirmed the good reproducibility level (ICC >0.75) of the questionnaire in both "physical functioning and activities of daily living" and "social life" domains and total score. The assessment of internal consistency in both domains of the questionnaire showed good internal consistency in visit 2. ICC showed the excellent agreement level between caregiver and patient in the global NutriQoL score. Finally, patients classified as having a minimal change in their health reported a mean (standard deviation) MCID in NutriQoL score of 0.63 (11.51).

CONCLUSION

NutriQoL is a reliable and unique instrument to measure the HRQoL in HEN patients. NutriQoL detects changes in the health status of the patient. Nevertheless, further research is needed to determine the full extent of the questionnaire responsiveness.

Development and validation of a specific questionnaire to assess health-related quality of life in patients with home enteral nutrition: NutriQoL® development

INTRODUCTION

Home enteral nutrition (HEN) is indicated in patients with a functional gastrointestinal tract but who are unable to meet their nutritional requirements with normally consumed foodstuffs. HEN allows patients to remain in their social and family environment, thus reducing complications and costs associated with hospital admission, while increasing health-related quality of life (HRQoL). HRQoL in patients with HEN is mainly evaluated by generic instruments, which are not sensitive enough to identify certain specific patient-related outcomes of HEN.

OBJECTIVE

To develop a specific instrument to measure HRQoL in patients receiving HEN whose results allow interpretation regardless of the underlying disease and nutritional support administration route: the NutriQoL^® questionnaire.

MATERIALS AND METHODS

The development of the NutriQoL entailed a literature review, focus groups with experts, semistructured interviews with patients, an assessment of face validity and feasibility, and Rasch analysis conducted on data from a sample of 141 patients and 24 caregivers.

RESULTS

Of the 52 items initially proposed on the basis of the literature review, expert focus group, and semi-structured interviews with patients and caregivers, 17 items were finally selected through the development process to make up the final version of the NutriQoL, as well as a visual analog scale for global HRQoL scoring. The selected items were evaluated as adequate for frequency, importance, and clarity. Furthermore, they have been shown to be independent of the underlying condition and HEN administration route.

CONCLUSION

A new instrument for measuring the HRQoL of patients with HEN in Spain has been developed, whose results are independent of the underlying condition and administration route. The next step will be the validation of the questionnaire to ensure that the instrument is valid, reliable, and sensitive to health status changes in patients, to be used periodically in usual clinical practice.