Responsiveness of Clinical Outcome Measures: An Investigation of Low Back Pain Patients Seen in the Primary and Secondary Sectors of the Danish Health Care System

Research output: ThesisPh.D. thesis

Abstract

Background

The Oswestry Disability Index (ODI) is one of two standardised functional health measurement scales (HMS) recommended. Despite extensive psychometric testing, little is known about HMS behaviour and the minimal clinically important difference (MCID) in subgroups of LBP patients. Moreover, the most commonly used retrospective method to establish the MCID has inherent methodological flaws. Perhaps it would be more prudent to ask LBP patients what is an acceptable result of the treatment before it begins?

Objectives

The overall objective was to establish the responsiveness and MCID in specific subgroups of patients with LBP. In addition, we explored whether low back pain patients were able to determine an acceptable treatment outcome before it began.

Methods

The responsiveness in subgroups study.
An extensive cross-cultural adaptation and validation of the ODI was carried out on patients seen in the primary (PrS) and secondary sectors (SeS) of the Danish health care system.

The prospective acceptable outcome study.
A method for estimating LBP patients' view of an acceptable change before treatment begins (MCIDpre was developed and compared to a well established retrospective method of determining the MCID (MCIDpost).

Results

The responsiveness in subgroups study.
The ODI measurement error ranged between -11.5 and +13 points. Responsiveness was comparable to the external measures. A floor effect was seen in the PrS patients. The MCID was nine points in PrS and LBP only patients and eight points in SeS and leg pain patients. Moreover, patients' retrospective evaluation of treatment effect was more responsive in PrS patients compared to serial measurements.

The prospective acceptable outcome study.
The prospective acceptable outcome method was reproducible. The MCIDpre was outside instrument measurement error and 1.5-4.5 times larger compared to the MCIDpost. Furthermore, the MCIDpre was almost comparable to patients' post-treatment acceptable change, but only for the pain scale.

Conclusion

The Danish version of the ODI is a reliable, valid and responsive HMS which is psychometrically more appropriate in SeS patients. In addition, the Roland Morris Disability Questionnaire (RMQ) is the most suitable for patients with LBP only whereas the ODI and RMQ is equally suitable for patients with leg pain. The choice of pain scale is arbitrary in all subgroups and the pain subscale of the Low Back Pain Rating Scale is recommended. The MCID was more or less stable across subgroups for most instruments and increased monotonously with baseline condition severity in PrS and LBP patients only.

The clinical question: “how are you now compared to when you started the treatment” seems to be most sensitive to condition alterations in PrS patients and should be added as an outcome measure to standard questionnaires used serially.

The prospective acceptable outcome method offers a benchmark by which clinicians can balance any mismatch between what are acceptable outcomes to the patient with what is realistically obtainable by a certain treatment. Chronic LBP patients seem to have a reasonable idea of an acceptable change in pain but overestimate change in functional and psychological /affective domains.

Original languageEnglish
Place of PublicationOdense
Publisher
Publication statusPublished - 2007

Keywords

  • Low back pain
  • Klinimetri
  • Måleinstrumenter
  • Funktion
  • Smerte
  • Spørgeskemaer
  • Sensitivity and Specificity
  • Mindste kliniske vigtige ændring
  • Mindste målbare ændring
  • Primær og sekundær sektor patienter
  • Transition spørgsmål

Fingerprint

Dive into the research topics of 'Responsiveness of Clinical Outcome Measures: An Investigation of Low Back Pain Patients Seen in the Primary and Secondary Sectors of the Danish Health Care System'. Together they form a unique fingerprint.

Cite this