Vijaya K Gothwal1, Deepak K Bagga2, Rebecca Sumalini2. 1. Meera and L.B. Deshpande Centre for Sight Enhancement, Vision Rehabilitation Centres, L.V. Prasad Eye Institute, Kallam Anji Reddy Campus, L.V. Prasad Marg, Banjara Hills, Hyderabad 500034, Andhra Pradesh, India. Electronic address: vijayagothwal@gmail.com. 2. Meera and L.B. Deshpande Centre for Sight Enhancement, Vision Rehabilitation Centres, L.V. Prasad Eye Institute, Kallam Anji Reddy Campus, L.V. Prasad Marg, Banjara Hills, Hyderabad 500034, Andhra Pradesh, India.
Abstract
BACKGROUND: The Patient-Health Questionnaire (PHQ-9) is a widely used screening instrument for depression. Recently, its properties as a measure were investigated using Rasch analysis in an Australian population with visual impairment (VI) and it was demonstrated to possess excellent measurement properties, but the response scale required shortening (modified PHQ-9). However, further validation was recommended to substantiate its use with the growing population of VI. Therefore, we aimed to use Rasch analysis to evaluate the measurement properties of the modified PHQ-9 in an Indian population with VI. METHODS: 303 patients with VI (mean age 40.2 years; 71% male) referred to Vision Rehabilitation Centres were administered the PHQ-9 by trained interviewer. Rasch analysis was used to investigate the psychometric properties of the modified PHQ-9. RESULTS: Rasch analysis showed good fit to the model, no misfitting items and an acceptable person separation reliability (0.82). Dimensionality testing supported combining 9 items to create a total score. Targeting was sub-optimal (-1.30 logits); more difficult items are needed. One item ('trouble falling asleep') showed notable differential item functioning, DIF (1.18 logits) by duration of VI. LIMITATIONS: The generalisability of these results might be restricted to patients with VI presenting to a tertiary eye care centre. CONCLUSIONS: Except for DIF, the performance of the modified PHQ-9 is consistent with that of the original, albeit in a different cultural context (Indian population with VI). Clinicians/researchers can readily use the modified PHQ-9 without formal training in Rasch procedures given the provision of ready-to-use spreadsheets that convert raw to Rasch-scaled scores. However the conversions will apply only if the sample being tested is similar to that of the present study.
BACKGROUND: The Patient-Health Questionnaire (PHQ-9) is a widely used screening instrument for depression. Recently, its properties as a measure were investigated using Rasch analysis in an Australian population with visual impairment (VI) and it was demonstrated to possess excellent measurement properties, but the response scale required shortening (modified PHQ-9). However, further validation was recommended to substantiate its use with the growing population of VI. Therefore, we aimed to use Rasch analysis to evaluate the measurement properties of the modified PHQ-9 in an Indian population with VI. METHODS: 303 patients with VI (mean age 40.2 years; 71% male) referred to Vision Rehabilitation Centres were administered the PHQ-9 by trained interviewer. Rasch analysis was used to investigate the psychometric properties of the modified PHQ-9. RESULTS: Rasch analysis showed good fit to the model, no misfitting items and an acceptable person separation reliability (0.82). Dimensionality testing supported combining 9 items to create a total score. Targeting was sub-optimal (-1.30 logits); more difficult items are needed. One item ('trouble falling asleep') showed notable differential item functioning, DIF (1.18 logits) by duration of VI. LIMITATIONS: The generalisability of these results might be restricted to patients with VI presenting to a tertiary eye care centre. CONCLUSIONS: Except for DIF, the performance of the modified PHQ-9 is consistent with that of the original, albeit in a different cultural context (Indian population with VI). Clinicians/researchers can readily use the modified PHQ-9 without formal training in Rasch procedures given the provision of ready-to-use spreadsheets that convert raw to Rasch-scaled scores. However the conversions will apply only if the sample being tested is similar to that of the present study.
Authors: Rebecca M Saracino; Ezgi Aytürk; Heining Cham; Barry Rosenfeld; Leah M Feuerstahler; Christian J Nelson Journal: Psychol Assess Date: 2019-08-08
Authors: Ashley D Deemer; Robert W Massof; Barry W Rovner; Robin J Casten; Catherine V Piersol Journal: Invest Ophthalmol Vis Sci Date: 2017-03-01 Impact factor: 4.799
Authors: Most Farida Khatun; Most Firoza Parvin; Md Mamun-Ur Rashid; Md Shah Alam; Most Kamrunnahar; Ashis Talukder; Shaharior Rahman Razu; Paul R Ward; Mohammad Ali Journal: Front Public Health Date: 2021-02-03