Measurement of Shoulder Outcomes

Carolyn M. Hettrich

Warren R. Dunn

John E. Kuhn

INTRODUCTION

As with all musculoskeletal conditions, outcome assessment of conditions affecting the shoulder should utilize a patientcentered approach. Careful consideration should be given to the clinical question and the disease state that is being studied in order to use an appropriate outcome measure when choosing which outcome measures to use. For maximum comparability and best overall assessment, a combination of general health with a region specific and disease or population-specific instrument is often used with or without additional metrics to measure activity level, comorbidities, or patient expectations. When choosing outcome tools, it is important to use a metric that has been rigorously validated. When performing research, such consideration is best given early in the study design process as the selected outcome instruments will be used to calculate the study’s sample size for a given power, based on an estimate of the desired, or clinically significant, effect of the investigation. When evaluating outcomes for a performance metric, patient satisfaction scales should be included.

When selecting from the outcome instruments available, the individual tools for measuring outcomes can be separated into discrete categories to include measures of general health, measures of upper extremity function, measures of shoulder activity level, shoulder-specific questionnaires, and condition or population-specific shoulder instruments.

The minimum clinically important difference (MCID) represents the smallest improvement considered worthwhile by a patient. This difference has to be determined for each outcome measure. While values less than this may be statistically significant, they are not clinically meaningful. This is of value in interpreting the literature and in power analyses.

Understanding how new measurement tools are created can help physicians to evaluate critically the instruments that are currently available. Major elements for the development of health-related quality of life tools include specifying measurement goals for the population being studied, question generation, item reduction, and questionnaire formatting. Question generation is carried out through reviewing the literature, interviewing experts, and interviewing patients with the condition being studied. The tool that was created then undergoes extensive pretesting, as well as testing for reliability (intra and inter-rater), responsiveness, validation, and interpretability. Interpretability places the magnitude of changes seen in the measurement tool in the context for people interpreting the results. This is best done by defining the MCID for each tool.³² Outcomes instruments developed using less rigorous methodology are more prone to biases and error.

More than 30 shoulder outcome measures have been described. The most popular and rigorously validated shoulder outcome measures for use in patient evaluation and research efforts are discussed in this chapter.

OUTCOME MEASURES

Measures of General Health

• Short Form-36 (SF-36)

• Short Form-12 (SF-12)

• Veterans RAND 36 Health Item Survey (VR-36)

• EuroQol-5D (EQ-5D)

Short Form-36

The SF-36 is the most widely used and best-established generic instrument for assessing physical, mental, and psychosocial health.⁵ It is based on eight health domains (vitality,
physical functioning, bodily pain, general health perceptions, physical role functioning, emotional role functioning, social role functioning, and mental health) that can be aggregated into two component summary scales (Physical Component Summary and Mental Component Summary) containing a total of 36 items.

The form is a registered trademark of the Medical Outcomes Study by RAND Health. Version 2 was copyrighted by QualityMetric Incorporated (2000) for commercial use. A commercial site, www.qualitymetric.com, provides information about obtaining a license to use the SF-36 v. 2 and an online version of the standard form. In addition, this site provides automated scoring that is normalized for the general population of the United States (an average score is 50 and the standard deviation is 10). In general, patients should complete the form at least 4 weeks following an incident that affects their health. An advantage of the SF-36 is the ability to convert to a preference-based measure of utility, the SF-6D, which can be used for cost utility analyses and comparative effectiveness research.

When a comprehensive overview of the patient’s state of health is required, a general outcome score should be included. For the SF-36, normative data are available in the United States and German populations, allowing for accurate comparisons of the relative degree of disability.¹⁰

Short Form-12

The Short Form-12 (version 2) is a 12-question version of the SF-36 that measures the same eight health domains with only one to two questions per domain. This can also be converted to a SF-6D. Information about usage and how to purchase licenses to use can be found at the same website, www.qualitymetric.com.

RAND

The Veterans RAND 36-Item Health Survey 1.0 includes the same items as those in the SF-36, but the recommended scoring algorithm is somewhat different for the general health and pain scales than that of the SF-36.²³ The RAND is available in the public domain license free from RAND, which is beneficial, as issues with licensing can be avoided.

There is also a Veterans RAND 12-Item Health Survey (VR-12), similar to the SF-12. A preference-based measure of utility has also been developed from the RAND, the VR-6D, which can be used for cost utility analyses and comparative effectiveness research. More information on the RAND can be found at http://www.rand.org/health/surveys_tools/mos/mos_core_36item.html.

EuroQol-5D

The EuroQol-5D is a five-question standardized instrument to measure health-related quality of life that can be used for clinical and economic analyses. There are five dimensions (mobility, self-care, usual activities, pain/discomfort, and anxiety/depression) and the EQ VAS—a 20 cm vertical visual analog scale that generates a self-rating of health-related quality of life. The EQ-5D has been well validated, and has been shown to be responsive. There are 102 official language versions, and population norms are available for 15 countries.

Written consent of the EuroQol Executive Office is required for use, and there may be licensing fees for usage.

Shoulder Activity Level

Scoring activity level is important, as a patient can decrease symptoms (and falsely elevate scores) by limiting his or her activity level. Use of these scores pre- and postoperatively can help assess any activity level changes. Measuring activity level can be very helpful after sports injuries as well.

The shoulder activity level metric was developed for use in addition to traditional scores that measure pain and function. It consists of five activities: carrying objects weighing ≥8 lb by hand, handling objects overhead, weight lifting or weight training with the arms, executing a swinging motion (swinging a baseball bat or golf club), and lifting objects weighing ≥25 lb. These five items are scored on a frequency basis from 0 to 4: performing the activity never to once per month (0 points), once per month (1 point), once per week (2 points), more than once per week (3 points), or daily (4 points). In addition, two questions determine whether the patient participates in contact sports or overhead throwing sports. The tool underwent reliability and validation testing during its development. Scores range from 0 (least active) to 20 (most active).⁹ Because the score is so new, it has been infrequently used in published studies, and the MCID has not been established

Measure of Upper Extremity Function

• Disabilities of the Arm, Shoulder, and Hand (DASH).

Disabilities of the Arm, Shoulder, and Hand

The DASH outcome measure is a 30-item, self-report questionnaire designed to measure physical function and symptoms in people with any of several musculoskeletal disorders of the upper limb. It was developed in 1996 by the Council of Musculoskeletal Specialty Societies, the American Academy of Orthopaedic Surgeons, and the Institute for Work and Health. The tool gives clinicians and researchers the advantage of having a single, reliable instrument that can be used to assess any or all joints in the upper extremity.²⁷

The DASH is a 30-item questionnaire that measures symptoms (six items, three of which concern pain) and function (24 items) of the upper extremity.⁷,⁴³ Originally, the DASH was a one-dimensional instrument, but subsequent division into subscales for pain and function has been well described.⁴ There are two optional modules (work and sports/music) available consisting of four items each, a work module and a sports/performing arts module. All questions reference the prior week, and each individual question is scored on a 5-point Likert scale. Up to three missing responses to items can be replaced by the mean value of the responses to the other items before summing.⁵³ Normative data have been established. While the survey was small (n = 1657), these population-based data are valid within its limitations (age- and sex-specific substrata in the United States).²⁸ The DASH has an MCID of 10.2 points.⁷ The DASH has been validated in many languages, including English, Swedish, Dutch, Chinese, Canadian French, German, Spanish, Brazilian Portuguese, Italian, Greek, Hungarian, Japanese, French, and Korean.¹⁷,²¹,²⁹,³⁶,⁴⁴,⁵⁰,⁵² The DASH has been specifically validated for glenohumeral arthritis and rotator cuff tendinitis, total shoulder arthroplasty, rotator cuff repair, and psoriatic arthritis.⁴,³⁹,⁴² Although it has not specifically been validated for other
entities, this score has been used to assess many shoulderspecific conditions.

Relative to other measures, the DASH allows for comparison of different conditions of the upper extremity, including different joints, and constitutes a comprehensive assessment of the whole arm.³,⁵ Further information on the DASH can be found at http://www.dash.iwh.on.ca/index.htm.

A shorter version called the QuickDASH was developed in 2005 to facilitate use, minimize the burden on the respondent, and minimize missing data. Only one missing item is permitted on the QuickDASH. Correlations between QuickDASH and DASH are extremely high (r > 0.97).⁸

In the latest edition of the AMA Guides to the Evaluation of Permanent Impairment, the QuickDASH is recommended as an adjunct to assess functional impairment when determining disability ratings related to the upper extremity.

Shoulder-Specific Measures

• American Shoulder and Elbow Surgeons (ASES)

• Constant Score

• Simple Shoulder Test (SST)

• Shoulder Pain and Disability Index (SPADI)

• Single Assessment Numeric Evaluation (SANE)

• University of California at Los Angeles (UCLA) Shoulder Scale

• Oxford Shoulder Score (OSS)

American Shoulder and Elbow Surgeons

The ASES score was developed in 1994 by the research committee of the ASES with the goal of creating a scoring system that could be applied to all patients regardless of diagnosis. It is a composite tool that involves both physician assessment as well as a patient-reported component (the physician portion is not commonly reported in the literature). The clinical assessment section provides scores on symptoms/pain (11 questions) and function (AROM, five questions). The patient self-assessment section is divided into three domains: pain, instability, and activities of daily living. The ASES does not have an established method for handling missing data.³³ The minimal clinically important difference is 6.4 points.⁴⁰ The ASES score has been validated in English and German in surgical and nonsurgical patients 20 to 81 years old.⁴⁰ The ASES has also been validated in patients with osteoarthritis (OA), shoulder instability, rotator cuff pathology, and shoulder arthroplasty.⁴,³⁵

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