Elsevier

General Hospital Psychiatry

Volume 21, Issue 1, January–February 1999, Pages 49-56
General Hospital Psychiatry

Original Articles
“INTERMED”: a method to assess health service needs: II. Results on its validity and clinical use

https://doi.org/10.1016/S0163-8343(98)00061-9Get rights and content

Abstract

The validity and clinical use of a recently developed instrument to assess health care needs of patients with a physical illness, called INTERMED, is investigated. The INTERMED combines data reflecting patients’ biological, psychological, and social characteristics with information on health care utilization characteristics. An example of a patient population in which such an integral assessment can contribute to the appropriateness of care, are patients with low back pain of degenerative or unknown origin. It supports the validity and the clinical usefulness of the INTERMED when clinically relevant subgroups in this heterogeneous population can be identified and described based on their INTERMED scores. The INTERMED was utilized in a group of patients (N = 108) having low back pain who vary on the chronicity of complaints, functional status, and associated disability. All patients underwent a medical examination and responded to a battery of validated questionnaires assessing biological, psychological, and social aspects of their life. In addition, the patients were assessed by the INTERMED. It was studied whether it proved to be possible to form clinically meaningful groups of patients based on their INTERMED scores; for this, a hierarchical cluster analysis was performed. In order to clinically describe them, the groups of patients were compared with the data from the questionnaires. The cluster analysis on the INTERMED scores revealed three distinguishable groups of patients. Comparison with the questionnaires assessing biological, psychological, and social aspects of disease showed that one group can be characterized as complex patients with chronic complaints and reduced capacity to work who apply for a disability compensation. The other groups differed explicitly with regard to chronicity, but also on other variables. By means of the INTERMED, clinically relevant groups of patients can be identified, which supports its use in clinical practice and its use as a method to describe case mix for scientific or health care policy purposes. In addition, the INTERMED is easy to implement in daily clinical practice and can be of help to ease the operationalization of the biopychosocial model of disease. More information on its validity in different patient populations is necessary.

Introduction

The INTERMED has been developed to integrate, in a standardized manner, the biopsychosocial aspects of disease with the organization of the health care system in an increasingly complex care delivery system 1, 2, 3. The documentation system is conceived for clinical (assessment of case complexity and health care needs), scientific (case mix description; stratification of populations in controlled trials), educational (problem-oriented teaching), and health care policy purposes (quality management). During its conceptualization and development, the face validity of its clinical variables have been extensively discussed among an international group of general hospital psychiatrists [4] and their colleagues from internal medicine, rheumatology, and palliative care. In a first study, the reliability of INTERMED has been evaluated by double scoring a series of patients [1]. In the present paper, the evaluation of the validity and clinical use of the INTERMED in a population with varying degrees of case complexity is reported.

Due to an increasing incidence of patients with benign low back pain in industrialized countries over the last decades [5] and the economic impact that a small minority with chronification and disability represents [6], major efforts have been undertaken to investigate this patient population. Meanwhile, it is well established that a clear correlation among biological variables, medical interventions, and course of disease is lacking 7, 8; that psychosocial factors play an important role, especially in those patients who become disabled 9, 10; and that combined medical and psychosocial interventions are more successful than medical interventions alone 11, 12. The impressive amount of knowledge about risk factors for low back pain disability related to biological [13], psychological 9, 10, sociodemographic [14], and social aspects [15] of the individual, as well as related to the medical [16], legal [17], and socioeconomic and sociocultural system [18] stresses that this patient population—especially the chronified and disabeled—is most adequately described in terms of co-morbidity and case complexity. These patients clearly vary on biological, psychological, and social variables and their medical care utilization. Low back pain patients therefore represent a suitable population to evaluate the validity of the INTERMED. If it is possible to distinguish clinically meaningful groups based on the integral data assessed with the INTERMED, this would support its validity and clinical use as a case mix instrument for the assessment of case complexity and health care needs.

Section snippets

Subjects

Subjects (N = 108) were recruited between November 1995 and November 1996 and were divided into two groups. Group 1 (N = 55) consisted of consecutive patients with acute, subacute, or chronic low back pain who were attending the department of Rheumatology outpatient clinic of the University Hospital of Lausanne. Group 2 (N = 53) consisted of consecutive patients with chronic low back pain applying for disability compensation at the center for disability evaluation of the University Medical

Sample

Due to major communication difficulties, five patients were excluded from the study. In addition, one patient refused participation, which lead to a definitive sample of 102 patients. Of these, there were two cases for which we did not have complete data on INTERMED, i.e., necessary to conduct hierarchical cluster analysis. Therefore, data analysis was performed on 100 patients, 49 of whom were applying for disability compensation. Table 2, Table 3 show the sociodemographic variables and

Discussion

The patients included in the study consist of two groups having similar principal complaints, i.e., benign low back pain, although having different medical and psychosocial characteristics, notably, applying for disability compensation or not. The INTERMED proves it possible to differentiate among three subgroups that differ from each other on a range of variables, seem to be homogeneous in themselves, and reflect clinically meaningful information.

The first group consists of patients with

Acknowledgements

This study has been supported by the Swiss National Foundation (Grant-No 3232-42162.95) and the European Union (grant BMH1-CT93-1180).

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