Several academic and policy organizations have proposed recommendations for translating health status instruments [19–21]. These different sets of recommendations are similar to one another. We adapted the World Health Organization protocol in translating the Yale Physical Activity Survey . The work was carried out by a primary translator (English to Spanish), a back-translator (Spanish to English) and a panel of investigators and lay persons from both the United States (US) and the Dominican Republic. The work proceeded in four stages: First, a native Spanish-speaking, Dominican-born nurse and medical student, who attended primary and secondary school in the Dominican Republic and college and medical school in the US, did the primary translation from English to Spanish. She attempted to identify and modify concepts that were not culturally sensitive. The translator’s work was reviewed by other bilingual Dominicans who grew up in the Dominican Republic and were not themselves health professionals. Other Dominican members of the research team provided input on the cultural sensitivity of word choice and of specific physical activities.
In the next phase, a non-Latino, English-speaking US resident, who is fluent in Spanish and had no prior knowledge of the YPAS, back-translated the measure from Spanish to English. Here too, the goal was to achieve the best possible conceptual translation, rather than literal, linguistic equivalence.
Two discrepancies between the original English YPAS and the back translation were easily resolved in a conference call that included the primary translator, back translator and several members of the research team (both Dominican and US).
Finally, the instrument was pretested by investigators, panel members and lay people in the Dominican Republic; these individuals comprised males and females and spanned a broad age range. This pilot work identified a few activities in the YPAS that the study population was unlikely to participate in (such as tennis), for either cultural or socioeconomic reasons. These were substituted for others (swimming and basketball) that are done more routinely and are similarly intensive.
The goal of this phase was convergent validation, in which we examined the associations between YPAS scores and other measures that we hypothesized to be associated with physical activity such as functional status and self-rated health.
The validation was fielded in the context of an annual mission trip of Operation Walk Boston, a philanthropic organization that performs approximately 45 total knee or hip replacements annually on Dominican persons with advanced hip or knee arthritis who otherwise would be unable to afford the surgery [22, 23]. The host institution is Hospital General de la Plaza de la Salud in Santo Domingo, Dominican Republic. This study was approved by the Institutional Review Board of the Brigham and Women’s Hospital and Partners HealthCare. Our research has also been approved by the Ethics Committee of Hospital General de la Plaza de la Salud. Formal written consent was not required since the study involved completing questionnaires with no interventions.
Patients admitted to the hospital for a total knee or hip replacement in April 2013 completed the Spanish version YPAS, along with a battery of other health status measures, preoperatively. In addition, patients returning to the annual follow up clinic in April 2013 who had received total hip or knee replacement in 2009, 2010, 2011 or 2012, also completed the YPAS along with other measures.
In addition to the YPAS, the questionnaires included the WOMAC (Western Ontario MacMaster Osteoarthritis Index) Pain and Function scales ; the Physical Activity Scale, 5-item Mental Health Scale and a single general health item (describe your health as excellent, good, fair, poor) from the SF-36 (Short Form 36) ; and the Euroqol EQ-5D questionnaire . We used published Spanish translations of these instruments and have documented the reliability and validity of the WOMAC and SF-36 scales in this Dominican population previously . We also collected data on the number of hips and knees that were painful and on subject age.
YPAS scoring and statistical analysis
Part I of the YPAS asks about the length of time subjects spend on specific activities in several domains (house work, yard work, care taking, exercise and recreation). These responses are aggregated to a number of minutes of each activity and then multiplied by a weight developed by the YPAS designers to yield total estimated energy expenditure. Part II asks about vigorous activities, leisurely walking, standing, moving about on one’s feet, sitting and stair climbing. This portion can be used to derive a total score (Activity Dimensions Summary Index; ADSI) as well as the number of minutes of vigorous activity and of walking. These vigorous activity and walking scores can, in turn, be used to develop a binary variable indicating whether the subject met the US Centers for Disease Control threshold of 75 minutes of vigorous activity per week or 150 minutes of vigorous or moderate activities per week, occurring in at least ten minute bouts.
We hypothesized that the total amount of activity (as represented by the YPAS Part II ADSI score) would be positively and modestly associated with greater functional status and quality of life. These hypotheses were addressed in bivariate Pearson correlation analyses. In further analyses, we hypothesized that the proportion of subjects meeting the CDC recommendations would be greater for those with better quality of life and fewer painful joints. We assessed these relationships using Fisher’s Exact test for the binary quality of life indicator and the Mantel-Haenszel test for trend for the ordinal painful joints indicator. As these validation analyses were somewhat exploratory, we accepted a critical p value of 0.05.