P. Moorer

Psychometric properties of the RAND-36 among three chronic disease (multiple sclerosis, rheumatic diseases and COPD) in the Netherlands

Objective: In this article, psychometric properties both of the total RAND-36 and of its subscales, such as unidimensionality, differential item functioning (DIF or item bias), homogeneity and reliabilities, are examined. Methods: The data from populations with three chronic illnesses, multiple sclerosis (n = 448), rheumatism (n = 336) and COPD (n = 259), have been collected in different parts of the Netherlands. The main technique used was Mokken scale analysis for polytomous items. Results: All subscales of the RAND-36 appeared to be unidimensional. For the sub scales ‘mental health’ and ‘general health perceptions’ some minor indications of DIF for the different chronic illnesses were found. Reliabilities of almost all subscales in all subpopulations were higher than 0.80, while the homogeneities of almost all subscales in all subpopulations were higher than 0.50, indicating ‘strong unidimensional, hierarchical scales’. Conclusions: In general, the subscales of the RAND-36 can be used to compare persons with different chronic illnesses. The subscale ‘general health perceptions’ did not function as well as would be preferred.

UNIDIMENSIONALITY AND CUMULATIVENESS OF THE LONELINESS SCALE USING MOKKEN SCALE ANALYSIS FOR POLYCHOTOMOUS ITEMS

The unidimensionality and cumulativeness of the Loneliness Scale of De Jong-Gierveld was investigated using the Mokken Scale Analysis for polychotomous items. 10 of the 11 items of the original Loneliness Scale constituted a unidimensional, cumulative scale, with a homogeneity coefficient H of 0.37 and a reliability coefficient rho of 0.88.

Health care utilization by people with multiple sclerosis in The Netherlands: results of two separate studies

Purpose : For chronically ill persons it is assumed that they make heavy demands on health care services. In the literature one hardly finds any publications to substantiate or refute this assumption. The main purpose of our study is to describe the health care utilization of people with multiple sclerosis (MS) in the Netherlands and its relationships with severity and duration of the disease. Methods : Two different samples of persons with MS were used. In the first sample (University Hospital Groningen) severity of MS was based on medical judgement, while in the second sample (Dutch Multiple Sclerosis Society) severity was self-reported. In both samples, use of health care facilities was assessed with a mail questionnaire. Results : The methods for determining severity resulted in different distributions for severity of MS. However, the results were quite similar with respect to health care utilization. It appeared that the severity of MS was related to the number of professional caretakers MS-patients had contact with during one year. Duration of MS seemed not to be related to the number of caretakers. Only for specific caretakers, most notably GP, physiotherapist, home help and ergotherapist, the contact frequency increased with severity of MS. No such relationship was found between the frequency of contact with the neurologist and severity of MS. Conclusions : People with MS do not make a heavy demand on health care facilities in general but only on certain health care provisions. This is in contrast with the general notion that all chronically ill make a heavy demand on health care facilities in general.

A STUDY OF THE UNIDIMENSIONALITY AND CUMULATIVENESS OF THE MOS SHORT-FORM GENERAL HEALTH SURVEY

The unidimensionality and cumulativeness of the subscales Health Perceptions, Mental Health, Physical Pain, and Social Functioning of the MOS Short-form General Health Survey were investigated using the Mokken Scale Analysis for Polychotomous Items (MSP). From the analyses, two unidimensional, cumulative subscales appeared, Health Perceptions including the item on Social Functioning, and Mental Health. Both subscales met the requirements of the Mokken model, with the first scale being a ‘moderately strong’ hierarchical scale (H = 0.49, rho = 0.89) and the second a ‘weak’ hierarchical scale (H = 0.38, rho = 0.85).