Table 1.

Properties of measures used for baseline and follow-up assessments

Instrument	Anticipated range	Reliability	Validity
Arthritis Self-Efficacy Scale • 8-item scale 1 (very uncertain) to 10 (very certain)	1-10	• The final 8-item scale had internal reliability ranging from Cronbach's α = 0.88 in the Cuban-origin group to Cronbach's α = 0.93 for the individuals of Mexican and Central American descent [16]. • The test-retest results revealed five items with weak correlations of r < 0.40. The items were found to have ambiguous wording, were redundant, and thus were removed from the scale.	• The proposed 8-item self-efficacy scale is based on translation and validation studies conducted in six geographic locations: five in the United States and one in Latin America [16].
Health Assessment Questionnaire Disability Index (HAQ-DI) • The 8-item scale measures areas of patient function: dressing and grooming, arising, reaching, gripping, eating, hygiene, walking and errands and chores.	1-3	• The test-retest reliability ranges from 0.87 to 0.96, with validity supported by a number of studies [32].	• The HAQ-DI has undergone extensive psychometric testing in diverse populations, including Hispanics. • Gonzalez et al. [16] conducted scaling, replication and test-retest studies to validate Spanish translations of the instrument. Internal consistency as measured by Cronbach's α was good, ranging from 0.87 to 0.89.
Wong-Baker Faces Pain Scale • Consists of six cartoon faces ranging from smiling face for "no pain" to tearful face for "worst pain" [33]. The scale includes facial expressions, numbers and words [34].	1-10	• Use of traditional pain scales has received mixed results in Hispanic populations. Gonzalez et al. [16] found that when comparing the Spanish version of the 0-10 Visual Analogue Pain Scale and Visual Numeric Pain Scale, the correlation was r = 0.72.	• The frequency of missing data was 24% for the Visual Analogue Scale and 6% for the Visual Numeric Scale. An individual's familiarity with the format of an instrument can influence the accuracy of the response [11].
• Short Acculturation Scale (SAS) Participants were asked to answer four items each with a five-point scale. • Each item was scored from 1 to 5. Scores were summed to create an acculturation scale ranging from 4 to 20. The higher the combined score, the more acculturated the respondent.	4-20	• Norris et al. [25] found the shorter four-item language subscale to be reliable, with a Cronbach's coefficient α of 0.80. • Wallen et al. [26] further evaluated the internal consistency of the SAS in a predominantly Central American population, with a Cronbach's coefficient α of 0.81.
Center for Epidemiologic Studies Depression Scale (CES-D) • CES-D 20-item scale was selected to reflect the following six components: depressed mood, feelings of guilt and worthlessness, helplessness and hopelessness, psychomotor retardation, loss of appetite and sleep disturbance during the past week. Responses to each item ranged from 1 (rarely or none of the time) to 3 (most or all of the time). Higher scores indicate a higher degree of symptomatology.	0-60	• Internal consistency of the measure has been good. Split-half correlations were reported as 0.85 for patient groups and 0.77 for normal groups. • Cronbach's coefficient α and Spearman-Brown coefficients were 0.90 or above for both volunteers and patients [35,36].	• The CES-D was validated in both household surveys and psychiatric settings. Test-retest reliability ranges have been reported from 0.32 for 12 months to 0.67 for 4 weeks.
		Spanish • A translation of the CES-D by the National Center for Health Statistics for the Hispanic Health and Nutrition Examination Survey (HHANES) was tested in both scaling (n = 272) and replication (n = 151) studies. The internal reliability for the 20-item scale was high (Cronbach's α = 0.90).	Spanish • The Spanish version of the CES-D is based on the translation and validation of arthritis outcome measures published by Gonzalez et al. [16].