Validity and reliability of the Marx Activity Rating Scale in patients from Mexico City.

Izaguirre A, Olivos A, Ibarra C, Marx R.

Background

• The number of outcome rating scales to measure patient function related to knee injury has increase in the past years.

• Lysholm and Knee injury and Osteoarthritis Outcome Score (KOOS), are disease specific questionnaires.

• When evaluating patients with knee diseases, besides measuring functionality, the level of activity is an important variable of interest.

Marx RG .Am J Sports Med 2001.

Background• The Marx activity scale. • This instrument is a patient reported

instrument, which is completed in approximately 1 minute, which facilitates its use with other instruments.– Running– Cutting – Deccelerating– Pivoting

Marx RG .Am J Sports Med 2001.

Purpose

• This useful instrument is not available for use in Spanish.

• Therefore, the purpose of this study was to perform a cross-cultural adaptation of the Marx activity scale into Spanish, and to evaluate validity, floor and ceiling effect, and reliability of this version in Mexican patients with knee injuries.

MethodsCross-Cultural Translation.

• Two orthopedic surgeons from Mexico, independently translated the Marx Activity Scale to Spanish.

• This provisional Spanish version was translated back to English by a qualified translator (mother tongue Spanish and fluent in English) and a clinical director (mother tongue English and fluent in Spanish).

• This back translation was reviewed against the source by the developers of Marx Activity Scale in order to check for discrepancies.

• The final Spanish was tested on ten patients with knee injuries to assess problems of comprehension of the questionnaire content.

MethodsPatients

• After approval of the Institutional Review Board, one-hundred patients with knee injuries were enroled to this study.

• The sample ws recruited in the outpatient clinic of the Service of Sports Orthopedic Surgery and Arthroscopy of the National Rehabilitation Institute, of Mexico City, Mexico.

Inclusion criteria were: 1. Age between 18 to 50 years, 2. Any gender,3. Diagnosis of ACL lesion, 4. Menisci lesion, 5. Chondral lesion, 6. Patellar dislocation,

osteoarthritis.

Exclusion criteria were:

1. Inflammatory arthritis 2. Inability of understand 3. Spanish written

language.

MethodsPatients

• Before patients were seen by their orthopedic surgeons at consult,– Lysholm– Tegner– KOOS – International Knee Documentation Committee

Subjective scale – Spanish version of the Marx Activity scale were

administered.

Methods Scales:The Lysholm score

• First described in 1982. • The score was designed to be physican

administered and measure outcomes after knee ligament surgery .

• 8 items which include, limp, support, locking, instability, pain, swelling, stair climbing and squatting.

Lysholm 1982 Am J Sports Med 1982

MethodsScales: The Tegner Activity Score

• 11 items with a a scoring range of 0-10; with higher scores representing higher levels of physical activity. – 6-10 corresponds to participation in

competitive/or recreational sports, – 1 to 5 corresponds to participation in recreational

sports and light to moderate heavy labors, – and 0 is recorded for disability. (4)

Tegner Y, Lysholm J. Clin Orthop Relat Res 19859.

MethodsScales: KOOS

• 42 item• Disease-specific questionnaire:– Pain (9 items)– Symptoms (7 items)– Activities of daily living (17 items)– Sport and Recreation (5 items) – Knee related Quality of Life (4 items). (7)

Roos EM, Toksvig-Larsen S. Health Qual Life Outcomes. 2003

MethodsMarx Activity Scale

• The Spanish version of Marx Activity Scale consists of 4 items

• It relates to the frequency with which the patient, runs, cuts, pivots and decelerates.

• Its score ranges from 0 to 16 with higher score representing higher activity level.

Marx RG .Am J Sports Med 2001.

Reproducibility.

• 20 healthy individuals with 18 to 50 years of age were submitted twice to the questionnaire (2 weeks)

• For all the cases the activity level remained constant while taking both questionnaires.

Construct Validity.

• Patients with high Spanish Marx Activity Scale scores would score higher Tegner Values.

• Patients with high Spanish Marx Activity Scale scores would score higher KOOS Sports and recreation values.

• For divergent validity, the Spanish Marx Activity Scale would correlate with patient age inversely.

Statistical Analyses.

• The intraclass correlation coefficient (ICC) was used to asses the instrument test-retest reliability. (0.8 good reliability)

• Spearman’s coeffient for correlations.– Strong correlation for values >0.5– Moderate correlation for values between 0.31 and

0.5– Weak correlations when < 0.31.

ResultsTranslation Process.

• During forward and backward translations, no major modification were made by the translators.

• In the pilot study no item was found to cause confusion by the respondents.

ResultsDemographics

• 100 patients for construct Validity.• Mean age was 35.89 ± 12.4. • 64 % were men compared to 36 women– ACL lesion in 40 patients– Meniscus lesion in 15 patients– Osteoarthritis in 31 patients – Patelofemoral disorders in 14 patients.

ResultsReproducibility

Test (n=20) Retest (n=20) ICC (95% CI)

Spanish Version of the Marx

Activity Scale

5.8 ± 3.75

6.5± 3.2

0.80 (0.72-0.95)

The intraclass correlation coefficient of the Spanish version of the Marx Activity Scale was of 0.8.

Construct Validity• Positive moderate

correlations – KOOS pain– Symptoms– ADL– Lysholm– Tegner IKDC subjective

form. KOOS

PainKOOS

SymptomsKOOSADL

KOOSSport/Rec

KOOSQoL

Lysholm IKDC-S Tegner Age

Marx Activity

Scale

0.357

p<0.001

0.359

p<0.001

0.315

p<0.001

0.183

p=0.06

0.04p=NS

0.3120.002

0.295

p=0.003

0.344

p=0.001

-0. 329

p=0.001

Moderate negative correlation – age.

Discussion

• The Spanish version of the Marx Activity scale has appropriate psychometric properties in terms of reliability, construct validity and ceiling and floor effects.

• With regard to construct validity, the Marx Activity scale had moderate correlation between KOOS in the subcales of pain, symptoms, activities of daily living.

• Spanish version of the Marx Activity scale does not correlate with the Sports and Recreation Subscale of KOOS.

Discussion

• Moderate positive correlation with the Tegner further confirms construct validity.

• This spanish version had a floor effect of 29%, close to the 33% margin set beforehand. Patients were studied preoperatively

Gracias