Applying multilevel item response theory to vision-related quality of life in Dutch visually impaired elderly

Ruth M A van Nispen, Dirk L Knol, Maaike Langelaan, Michiel R de Boer, Caroline B Terwee, Ger H M B van Rens

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

PURPOSE: Instead of applying the usual longitudinal methods to assess the outcome of low-vision rehabilitation services in terms of vision-related quality of life, a three-level Item Response Theory (IRT) method was proposed.

METHODS: The translated Vision-Related Quality of Life Core Measure (VCM1) and Low Vision Quality Of Life (LVQOL) questionnaires were used in a nonrandomized follow-up study among elderly patients (n = 296) referred to two different low-vision rehabilitation services in the Netherlands. Factor analysis was performed on the matrix of polychoric correlations to investigate (uni-)dimensionality and to prepare both questionnaires for the multilevel IRT analyses. A statistical model, which was characterized by a graded response model for rating scales, was developed. Threshold and item difficulty parameters and group by time-specific mean fixed effects were estimated. Random individual effects were predicted. Measurement invariance across occasions was tested.

RESULTS: The VCM1 and the LVQOL "reading and fine work" dimension showed item parameter drift. In the multidisciplinary rehabilitation center patients, deterioration was found on the "mobility" dimension after 1 year and improvement was found on "adjustment" and "visual (motor) skills" after 5 months (p < 0.05). Patients in both low-vision services showed improvement on the "reading small print" subscale at both follow-up time points (p < 0.05).

CONCLUSIONS: Except for improvement in "reading small print," low-vision rehabilitation services did not seem to contribute substantially to any other dimensions of vision-related quality of life. The results showed a change in only a limited number of individual patients. However, with regard to the field of low-vision rehabilitation, the proposed IRT method seemed to be successful in the follow-up of individuals. IRT specific software was unnecessary. The data did not have to be complete and the use of cumulative logits made the proposed IRT method an economical and efficient approach. Because of item parameter drift, the VCM1 was difficult to interpret. The use of multilevel IRT models with longitudinal data and dependent observations is recommended.

Original languageEnglish
Pages (from-to)710-20
Number of pages11
JournalOptometry and Vision Science
Volume84
Issue number8
DOIs
Publication statusPublished - Aug 2007

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Low Vision
Quality of Life
Rehabilitation
Reading
Social Adjustment
Rehabilitation Centers
Motor Skills
Statistical Models
Netherlands
Statistical Factor Analysis
Software

Keywords

  • Aged
  • Aged, 80 and over
  • Female
  • Follow-Up Studies
  • Humans
  • Male
  • Models, Psychological
  • Models, Statistical
  • Netherlands
  • Outcome Assessment (Health Care)
  • Psychometrics
  • Quality of Life
  • Surveys and Questionnaires
  • Vision, Low
  • Visual Acuity
  • Journal Article
  • Research Support, Non-U.S. Gov't

Cite this

van Nispen, Ruth M A ; Knol, Dirk L ; Langelaan, Maaike ; de Boer, Michiel R ; Terwee, Caroline B ; van Rens, Ger H M B. / Applying multilevel item response theory to vision-related quality of life in Dutch visually impaired elderly. In: Optometry and Vision Science. 2007 ; Vol. 84, No. 8. pp. 710-20.
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Applying multilevel item response theory to vision-related quality of life in Dutch visually impaired elderly. / van Nispen, Ruth M A; Knol, Dirk L; Langelaan, Maaike; de Boer, Michiel R; Terwee, Caroline B; van Rens, Ger H M B.

In: Optometry and Vision Science, Vol. 84, No. 8, 08.2007, p. 710-20.

Research output: Contribution to JournalArticleAcademicpeer-review

TY - JOUR

T1 - Applying multilevel item response theory to vision-related quality of life in Dutch visually impaired elderly

AU - van Nispen, Ruth M A

AU - Knol, Dirk L

AU - Langelaan, Maaike

AU - de Boer, Michiel R

AU - Terwee, Caroline B

AU - van Rens, Ger H M B

PY - 2007/8

Y1 - 2007/8

N2 - PURPOSE: Instead of applying the usual longitudinal methods to assess the outcome of low-vision rehabilitation services in terms of vision-related quality of life, a three-level Item Response Theory (IRT) method was proposed.METHODS: The translated Vision-Related Quality of Life Core Measure (VCM1) and Low Vision Quality Of Life (LVQOL) questionnaires were used in a nonrandomized follow-up study among elderly patients (n = 296) referred to two different low-vision rehabilitation services in the Netherlands. Factor analysis was performed on the matrix of polychoric correlations to investigate (uni-)dimensionality and to prepare both questionnaires for the multilevel IRT analyses. A statistical model, which was characterized by a graded response model for rating scales, was developed. Threshold and item difficulty parameters and group by time-specific mean fixed effects were estimated. Random individual effects were predicted. Measurement invariance across occasions was tested.RESULTS: The VCM1 and the LVQOL "reading and fine work" dimension showed item parameter drift. In the multidisciplinary rehabilitation center patients, deterioration was found on the "mobility" dimension after 1 year and improvement was found on "adjustment" and "visual (motor) skills" after 5 months (p < 0.05). Patients in both low-vision services showed improvement on the "reading small print" subscale at both follow-up time points (p < 0.05).CONCLUSIONS: Except for improvement in "reading small print," low-vision rehabilitation services did not seem to contribute substantially to any other dimensions of vision-related quality of life. The results showed a change in only a limited number of individual patients. However, with regard to the field of low-vision rehabilitation, the proposed IRT method seemed to be successful in the follow-up of individuals. IRT specific software was unnecessary. The data did not have to be complete and the use of cumulative logits made the proposed IRT method an economical and efficient approach. Because of item parameter drift, the VCM1 was difficult to interpret. The use of multilevel IRT models with longitudinal data and dependent observations is recommended.

AB - PURPOSE: Instead of applying the usual longitudinal methods to assess the outcome of low-vision rehabilitation services in terms of vision-related quality of life, a three-level Item Response Theory (IRT) method was proposed.METHODS: The translated Vision-Related Quality of Life Core Measure (VCM1) and Low Vision Quality Of Life (LVQOL) questionnaires were used in a nonrandomized follow-up study among elderly patients (n = 296) referred to two different low-vision rehabilitation services in the Netherlands. Factor analysis was performed on the matrix of polychoric correlations to investigate (uni-)dimensionality and to prepare both questionnaires for the multilevel IRT analyses. A statistical model, which was characterized by a graded response model for rating scales, was developed. Threshold and item difficulty parameters and group by time-specific mean fixed effects were estimated. Random individual effects were predicted. Measurement invariance across occasions was tested.RESULTS: The VCM1 and the LVQOL "reading and fine work" dimension showed item parameter drift. In the multidisciplinary rehabilitation center patients, deterioration was found on the "mobility" dimension after 1 year and improvement was found on "adjustment" and "visual (motor) skills" after 5 months (p < 0.05). Patients in both low-vision services showed improvement on the "reading small print" subscale at both follow-up time points (p < 0.05).CONCLUSIONS: Except for improvement in "reading small print," low-vision rehabilitation services did not seem to contribute substantially to any other dimensions of vision-related quality of life. The results showed a change in only a limited number of individual patients. However, with regard to the field of low-vision rehabilitation, the proposed IRT method seemed to be successful in the follow-up of individuals. IRT specific software was unnecessary. The data did not have to be complete and the use of cumulative logits made the proposed IRT method an economical and efficient approach. Because of item parameter drift, the VCM1 was difficult to interpret. The use of multilevel IRT models with longitudinal data and dependent observations is recommended.

KW - Aged

KW - Aged, 80 and over

KW - Female

KW - Follow-Up Studies

KW - Humans

KW - Male

KW - Models, Psychological

KW - Models, Statistical

KW - Netherlands

KW - Outcome Assessment (Health Care)

KW - Psychometrics

KW - Quality of Life

KW - Surveys and Questionnaires

KW - Vision, Low

KW - Visual Acuity

KW - Journal Article

KW - Research Support, Non-U.S. Gov't

U2 - 10.1097/OPX.0b013e31813375b8

DO - 10.1097/OPX.0b013e31813375b8

M3 - Article

VL - 84

SP - 710

EP - 720

JO - Optometry and Vision Science

JF - Optometry and Vision Science

SN - 1040-5488

IS - 8

ER -