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Abbreviated World Health Organization Quality of Life questionnaire (WHOQOL-Bref) in north Indian patients with bronchial asthma: an evaluation using Rasch analysis.

Aggarwal AN, Agarwal R, Gupta D - NPJ Prim Care Respir Med (2014)

Bottom Line: Item 3 (pain prevents doing work) displayed a large positive fit residual value (indicating violation of unidimensionality), resulting in poor construct validity for the physical domain.The modified scale had good construct validity for all domains, ordered thresholds for all items and good targeting of items to persons.However, when modified by Rasch analysis, the scale proved better than the original scale.

View Article: PubMed Central - PubMed

Affiliation: Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh, India.

ABSTRACT

Background: There is no disease-specific instrument to describe health-related quality of life (HRQoL) in Indian patients with asthma. However, an abbreviated World Health Organization Quality of Life questionnaire (WHOQOL-Bref), a generic Hindi HRQoL measure, has been developed and validated in India.

Aims: To evaluate the WHOQOL-Bref in adult patients with asthma and to test possible modifications to the instrument to improve its psychometric adequacy.

Methods: Sixty-seven patients with asthma completed the WHOQOL-Bref. Rasch analysis was used to explore the psychometric performance of the four domains (physical, psychological, social relationships and environment) of the scale. Overall fit of data to model expectations, appropriate category ordering, presence of differential item functioning, individual item fit and targeting of item difficulty to patient ability were explored for each domain. Item deletion and rescoring were applied to misfitting items to improve overall performance.

Results: The overall fit of the WHOQOL-Bref data was adequate. Item 3 (pain prevents doing work) displayed a large positive fit residual value (indicating violation of unidimensionality), resulting in poor construct validity for the physical domain. No item exhibited differential item functioning. Ten items had disordered thresholds. The WHOQOL-Bref was modified by dropping item 3 and rescoring category structures of 16 items. The modified scale had good construct validity for all domains, ordered thresholds for all items and good targeting of items to persons.

Conclusions: The WHOQOL-Bref performed inadequately in describing HRQoL in the asthma patients studied. However, when modified by Rasch analysis, the scale proved better than the original scale.

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Related in: MedlinePlus

Person-item distribution maps for various domains of the abbreviated World Health Organization Quality of Life (WHOQOL-Bref) after rescoring categories. The vertical line represents the measure of the variable in linear logit units. In each panel, the right-hand column locates questionnaire item threshold difficulty measures along the variable. Each entry is indicated by its number in the original questionnaire (see Table 1), followed by the threshold after the decimal point. For instance, the location 04.3 refers to the difficulty calibration estimate of the third threshold (i.e., threshold between the third and fourth response category) of the fourth questionnaire item. The left-hand column locates the patients’ ability measure along the variable, with each plus sign representing 10 patients and each circle representing one patient. From bottom to top, measures indicate better health-related quality of life (for patients) and greater difficulty (for items).
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fig3: Person-item distribution maps for various domains of the abbreviated World Health Organization Quality of Life (WHOQOL-Bref) after rescoring categories. The vertical line represents the measure of the variable in linear logit units. In each panel, the right-hand column locates questionnaire item threshold difficulty measures along the variable. Each entry is indicated by its number in the original questionnaire (see Table 1), followed by the threshold after the decimal point. For instance, the location 04.3 refers to the difficulty calibration estimate of the third threshold (i.e., threshold between the third and fourth response category) of the fourth questionnaire item. The left-hand column locates the patients’ ability measure along the variable, with each plus sign representing 10 patients and each circle representing one patient. From bottom to top, measures indicate better health-related quality of life (for patients) and greater difficulty (for items).

Mentions: In view of the rather suboptimal performance of the WHOQOL-Bref (significant item–trait interaction for the physical domain, anomalous threshold patterns for several items and lack of selection of few response options by any respondent), the scale was modified by dropping item 3 and collapsing two or more response categories of 16 items (see Supplementary Table S3). The rescored instrument had better construct validity as the previously significant item–trait interaction for the physical domain became insignificant (Table 2). However, the person-separation index did not substantially improve for any domain, indicating that the ability of the revised questionnaire to separate patients with different HRQoL remained largely similar. Overall fit parameters remained satisfactory (Table 2) and threshold analysis revealed ordered thresholds for all items (see Supplementary Table S3 and Figure 2). Person location estimates remained acceptable (Table 2). Person-item maps confirmed that the modified scale was well targeted to the patient population as almost all person ability estimates were well matched by one or more response thresholds (Figure 3). Formal statistical analysis did not demonstrate any DIF (Supplementary Table S2).


Abbreviated World Health Organization Quality of Life questionnaire (WHOQOL-Bref) in north Indian patients with bronchial asthma: an evaluation using Rasch analysis.

Aggarwal AN, Agarwal R, Gupta D - NPJ Prim Care Respir Med (2014)

Person-item distribution maps for various domains of the abbreviated World Health Organization Quality of Life (WHOQOL-Bref) after rescoring categories. The vertical line represents the measure of the variable in linear logit units. In each panel, the right-hand column locates questionnaire item threshold difficulty measures along the variable. Each entry is indicated by its number in the original questionnaire (see Table 1), followed by the threshold after the decimal point. For instance, the location 04.3 refers to the difficulty calibration estimate of the third threshold (i.e., threshold between the third and fourth response category) of the fourth questionnaire item. The left-hand column locates the patients’ ability measure along the variable, with each plus sign representing 10 patients and each circle representing one patient. From bottom to top, measures indicate better health-related quality of life (for patients) and greater difficulty (for items).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4373256&req=5

fig3: Person-item distribution maps for various domains of the abbreviated World Health Organization Quality of Life (WHOQOL-Bref) after rescoring categories. The vertical line represents the measure of the variable in linear logit units. In each panel, the right-hand column locates questionnaire item threshold difficulty measures along the variable. Each entry is indicated by its number in the original questionnaire (see Table 1), followed by the threshold after the decimal point. For instance, the location 04.3 refers to the difficulty calibration estimate of the third threshold (i.e., threshold between the third and fourth response category) of the fourth questionnaire item. The left-hand column locates the patients’ ability measure along the variable, with each plus sign representing 10 patients and each circle representing one patient. From bottom to top, measures indicate better health-related quality of life (for patients) and greater difficulty (for items).
Mentions: In view of the rather suboptimal performance of the WHOQOL-Bref (significant item–trait interaction for the physical domain, anomalous threshold patterns for several items and lack of selection of few response options by any respondent), the scale was modified by dropping item 3 and collapsing two or more response categories of 16 items (see Supplementary Table S3). The rescored instrument had better construct validity as the previously significant item–trait interaction for the physical domain became insignificant (Table 2). However, the person-separation index did not substantially improve for any domain, indicating that the ability of the revised questionnaire to separate patients with different HRQoL remained largely similar. Overall fit parameters remained satisfactory (Table 2) and threshold analysis revealed ordered thresholds for all items (see Supplementary Table S3 and Figure 2). Person location estimates remained acceptable (Table 2). Person-item maps confirmed that the modified scale was well targeted to the patient population as almost all person ability estimates were well matched by one or more response thresholds (Figure 3). Formal statistical analysis did not demonstrate any DIF (Supplementary Table S2).

Bottom Line: Item 3 (pain prevents doing work) displayed a large positive fit residual value (indicating violation of unidimensionality), resulting in poor construct validity for the physical domain.The modified scale had good construct validity for all domains, ordered thresholds for all items and good targeting of items to persons.However, when modified by Rasch analysis, the scale proved better than the original scale.

View Article: PubMed Central - PubMed

Affiliation: Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh, India.

ABSTRACT

Background: There is no disease-specific instrument to describe health-related quality of life (HRQoL) in Indian patients with asthma. However, an abbreviated World Health Organization Quality of Life questionnaire (WHOQOL-Bref), a generic Hindi HRQoL measure, has been developed and validated in India.

Aims: To evaluate the WHOQOL-Bref in adult patients with asthma and to test possible modifications to the instrument to improve its psychometric adequacy.

Methods: Sixty-seven patients with asthma completed the WHOQOL-Bref. Rasch analysis was used to explore the psychometric performance of the four domains (physical, psychological, social relationships and environment) of the scale. Overall fit of data to model expectations, appropriate category ordering, presence of differential item functioning, individual item fit and targeting of item difficulty to patient ability were explored for each domain. Item deletion and rescoring were applied to misfitting items to improve overall performance.

Results: The overall fit of the WHOQOL-Bref data was adequate. Item 3 (pain prevents doing work) displayed a large positive fit residual value (indicating violation of unidimensionality), resulting in poor construct validity for the physical domain. No item exhibited differential item functioning. Ten items had disordered thresholds. The WHOQOL-Bref was modified by dropping item 3 and rescoring category structures of 16 items. The modified scale had good construct validity for all domains, ordered thresholds for all items and good targeting of items to persons.

Conclusions: The WHOQOL-Bref performed inadequately in describing HRQoL in the asthma patients studied. However, when modified by Rasch analysis, the scale proved better than the original scale.

Show MeSH
Related in: MedlinePlus