While talking to a fellow Elf recently at the World Congress of Active Ageing in Glasgow this week about the core set of outcome measures that have been introduced across Scotland as part of its re-designed musculoskeletal pathways (NHS Scotland, 2012) she asked me an interesting question: “do you think that a patient-specific functional scale (PSFS) should have been included?” This got me thinking.

Patient reported outcome measures (PROMs) are receiving considerable interest in healthcare at present as providers aim to demonstrate the quality and impact of their services. However, one of the problems with many physical function self-report outcome measures is that they have ‘fixed-items’ that may not always be relevant to patients’ needs and do not consider their preferences. For example, scoring the patient’s ability to perform gardening is of low relevance to someone who does not have a garden. Therefore, there has been a recent surge in the development of patient-specific outcome measures; these are when a patient identifies issues and activities that are relevant to them and outcomes focus on evaluating these over time.

Therefore, it was with great interest that I found a systematic review of the psychometric properties of patient-specific self-assessment instruments that measure physical function in patients with musculoskeletal disorders by Barten et al (2012) in the Journal of Clinical Epidemiology. Perhaps this would help me answer my colleague’s question as to whether or not a PSFS should have been included or not.

Here’s what they did

A search strategy was conducted in PubMed, CINAHL and EMBASE (up until December 2011) that included instruments with a patient-specific character that measure physical function in people with musculoskeletal disorders. Psychometric quality was determined using the standardised checklist “quality criteria for measurement properties of health status questionnaires” (Terwee et al, 2007). 

Here’s what they found

1,617 unique articles were identified; after the inclusion criteria were applied 23 studies were included that referred to 12 different instruments:

1. Canadian Occupational Performance Measure (COPM);
2. Individualized Health Assessment Questionnaire Disability Index (I-HAQ-DI);
3. Individualized Milliken Activities of Daily Living Scale (IMAS);  
4. Interviewer-administrated Patient-Specific Index (I-PSI);
5. Individualized Western Ontario and McMaster Universities Osteoarthritis Index (I-WOMAC);
6. McMaster Toronto Arthritis Patient Preference Disability Questionnaire (MACTAR);
7. Patient-Specific Approach (PSA);
8. Patient-Specific Activity Questionnaire (PSAQ);
9. Patient-Specific Disabilities of the Arm, Shoulder and Hand questionnaire (PS-DASH);
10. Patient-Specific Functional Scale (PSFS);
11. Severity of the Main Complaints Scale (SMCS); and
12. Self-Reported Patient-Specific Index (S-PSI).

Of the included instruments:

• nine were different versions of the patient-specific functional scale (PSFS), showing its recent popularity;
• none of them evaluated all of the measurement properties proposed by Terwee et al (2007);
• the PSFS by Cleland et al (2006) achieved the highest score with positive scoring for construct validity, reproducibility and responsiveness.

The authors concluded:

“The descriptive properties and psychometric quality of patient-specific instruments measuring physical function are only partly investigated. The PSFS was the most investigated instrument: nine different versions have been evaluated psychometrically. The version of Cleland et al. was most extensively investigated and could be recommended for clinical use.”

The Musculoskeletal Elf’s views

Although the PSFS by Cleland et al received the highest score, it would have to be noted that it was only evaluated on 38 individuals with cervical radiculopathy; therefore, it is difficult to generalise these findings to a wider population and to other musculoskeletal conditions. Furthermore, it only achieved a score of  four out of a possible eight positive scores.

Future research is necessary to confirm the psychometric quality of patient-specific instruments measuring physical function in patients with musculoskeletal disorders. In particular more substantial research on floor and ceiling effects of these types of instruments is required.

Therefore, in answer to my fellow Elf’s question – I think that it was the right decision not to include any patient-specific functional scales at this stage in their development in any musculoskeletal core set of outcome measures.

Do you use any patient-specific functional scales? What is your view on this review, will it change your clinical practice? Send us your views on this blog and become part of the Musculoskeletal Elf community.

Links

NHS Scotland (2012) “18 weeks Scotland’s referral to treatment standard”, http://www.18weeks.scot.nhs.uk/service-redesign-and-transformation/musculoskeletal-services/ [accessed 25th July, 2012]

Barten, J.A., Pisters, M.F., Huisman, P.A., Takken, T. & Veenhof, C. 2012, “Measurement properties of patient-specific instruments measuring physical function”, Journal of clinical epidemiology, Vol. 65, no. 6, pp. 590-601. [PubMed abstract]

Terwee, C.B., Bot, S.D.M., de Boer, M.R., van der Windt, D.A.W.M., Knol, D.L., Dekker, J., et al. 2007, “Quality criteria were proposed for measurement properties of health status questionnaires”, Journal of clinical epidemiology, Vol. 60, no. 1, pp. 34-42. [PubMed abstract]

Cleland, J.A., Fritz, J.M., Whitman, J.M., Palmer, J.A. 2006 “The reliability and construct validity of the Neck Disability Index and patient specific functional scale in patients with cervical radiculopathy.”, Spine, Vol. 1, no. 5, pp. 598-602 [PubMed abstract]

COnsensus-based Standards for the selection of healthMeasurement INstruments (COSMIN)  http://www.cosmin.nl/ [accessed 25th July, 2012]