Table_1_Four Methods of Recruiting Couples Into a Longitudinal Study of Physical Activity in People With Osteoarthritis: Recruitment, Retention, and Lessons Learned.DOCX

<p>Increases in physical activity can reduce joint pain among people with osteoarthritis (PWOA) who are insufficiently physically active. Because evidence suggests that social support from intimate partners may help PWOA become more active, researchers have been interested in recruiting couples to studies of physical activity interventions; however, little guidance exists describing efficient and effective strategies for engaging couples in research. We describe methods used to recruit couples and contrast methods in terms of the proportion of individuals enrolled, sample demographic composition, retention, and resources. We used four recruitment methods to enroll couples in a longitudinal study of PWOA: (1) visiting community sites, (2) sending university-wide emails, (3) contacting patients identified through electronic medical records (EMR), and (4) partnering with a county-based osteoarthritis (OA) research cohort. We found that these methods differed in their challenges and contribution to enrollment goals but demonstrated similar levels of retention. We contacted 747 PWOA; 56% were screened for eligibility and 23% enrolled in the study. The largest proportion of participants recruited were from the email method (35.1%), followed by the community (26%), EMR (22.0%), and OA cohort (19.6%). Couples enrolled through the different methods differed by age, employment, education, and household income. Across the methods for both PWOA and partners, over 80% of participants were non-Hispanic white, about 11% were non-Hispanic black, and 6–8% identified as another race. Over 12 months of follow-up, 31 (17.9%) PWOA and 36 (20.8%) partners were lost to follow-up. Using four distinct recruitment methods allowed us to meet recruitment goals and provided a broader, more diverse population compared to using one method. We recommend that researchers consider several recruitment methods to meet enrollment goals, to ensure a diverse sample, and to match available resources. The lessons learned from this research fill a critical gap in the understanding of how to overcome barriers to recruiting and retaining couples in behavioral research.</p

Only SNPs genotyped in this study are listed by name.

<p>SNPs in linkage disequilibrium with SNPs genotyped in this study are shown in brown. SNPs in gray were not genotyped or haplotype tagged due to low minor allele frequency (MAF). SNP - Single Nucleotide Polymorphism. 5251* is not yet registered in dbSNP as described in the <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1000424#s2" target="_blank">methods</a>.</p

Odds ratios for the protective effect of the rs231778 G allele in African Americans with RA.

<p>Analysis compares number of patients and controls for genotype AA vs those with either AG or GG in a 2×2 Fisher's exact test. OR – odds ratio; CI – confidence interval.</p

Association with rheumatoid arthritis at rs231778 in African Americans.

<p>Values indicate number of samples with allele frequency in parentheses. Analysis compares number of patients and controls for each genotype (AA vs AG vs GG) in a 3×2 Fisher's exact test.</p

This plot, generated from HaploView v3.31 (Broad Institute), shows the r² values between SNPs genotyped in <i>CTLA4</i>.

<p>Darker boxes represent stronger r² values. 5251* is not yet registered in dbSNP as described in the <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1000424#s2" target="_blank">methods</a>.</p

Mean percentage of European ancestry segregated by genotype of rs231778.

<p>This table provides data for the 347 samples with complete admixture and rs231778 genotyping data. Standard error is provided in parenthesis. Brackets indicate frequency counts used in determining association of the rs231778 G allele with rheumatoid arthritis among 366 samples, as described in the text.</p

Minor allele frequency (MAF) of rs231778 segregated by HLA-DRB1 shared epitope status.

<p>This table combines samples from both CLEAR I and CLEAR II and only incorporates data where HLA-DRB1 shared epitope (SE) status has been determined. The ‘N’ listed below each MAF represents the number of ‘G’ alleles over the total number of alleles for each number of SE alleles present. SE – <i>HLA-DRB1</i> shared epitope.</p

Minor allele frequencies of CTLA4 SNPs for African American RA patients and controls.

<p>This table represents combined data from CLEAR I and CLEAR II. rs3087243 (+60C/T) has been associated with RA in Caucasians, and rs231775 (+49A/G) has been associated with other autoimmune conditions. Position is the physical location of each polymorphism relative to the start codon (position = 0) in dbSNP build 129. CCP refers to anti-cyclic citrullinated antibody status. SE refers to presence of HLA-DRB1 shared epitope. Public databases include allele frequencies from HapMap or SeattleSNP. rs231776 was not in Hardy-Weinberg Equilibrium. *5251 is not currently listed in dbSNP as described in the <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1000424#s2" target="_blank">methods</a>.</p