There has been an increase in the use of electronic systems to collect patient-reported outcome measures. There is limited data on the added value of electronic reporting on increasing patient response proportions and little knowledge of which patients are more likely to respond. (1) What proportion of patients completed patient-reported outcome questionnaires at baseline and at 1 year and 2 years of follow-up after shoulder arthroplasty, and what methods did they use to complete these questionnaires (either automated or manual data collection)? (2) What factors were associated with questionnaire completion? Our shoulder arthroplasty registry from a high-volume, tertiary care center implemented an electronic platform to collect patient-reported outcomes. A total of 2128 patients underwent shoulder arthroplasty between 2016 and 2019. Patients without an email address on file were excluded; 90% (1907 of 2128) of patients were included in the study. The population was 50% women (954 of 1907) with a mean age of 67 ± 9 years. A query was performed to determine whether patients completed questionnaires by either automated or manual data collection at baseline and 1 year and 2 years of follow-up after shoulder arthroplasty. In a logistic regression analysis, patient factors (such as demographics, education, and living arrangements) were evaluated for their association with whether patients completed these questionnaires. The proportion of questionnaire completion at baseline, 1 year, and 2 years were 72% (1369 of 1907), 47% (456 of 972), and 33% (128 of 393), respectively. Of the patients who completed their questionnaires, 63% (868 of 1369) did so through automated emails at baseline, 84% (381 of 456) did so at 1 year, and 81% (103 of 128) did so at 2 years. The remainder completed their questionnaires through manual data collection with a research assistant: 37% (501 of 1369) at baseline, 16% (75 of 456) at 1 year, and 19% (25 of 128) at 2 years. After controlling for potentially confounding variables like patient demographics, college education, and living arrangements, women were less likely to complete baseline questionnaires than men (odds ratio 0.78 [95% confidence interval 0.62 to 0.99]; p = 0.04), and white patients (OR 1.6 [95% CI 1.05 to 2.44]; p = 0.03) were more likely than nonwhite patients to have complete baseline questionnaires. At 2 years of follow-up, patients with a college education (OR 2.06 [95% CI 1.14 to 3.71]; p = 0.02), those who lived alone (OR 2.11 [95% CI 1.13 to 3.94]; p = 0.02), and those who had higher baseline Shoulder Activity Scale scores (OR 1.05 [95% CI 1.00 to 1.11]; p = 0.04) were more likely to have complete questionnaires than those without a college education, those who lived with other people, and those with lower SAS scores, respectively. The challenges of adopting an online platform include low follow-up proportions and the need for manual assistance by a research assistant to increase patient completion of questionnaires. The knowledge of which patient characteristics are associated with a higher likelihood of completing questionnaires has implications for targeted follow-up or representative sampling of the population in a registry. Populations that are less likely to respond may require more effort to reach to prevent exacerbating health outcome disparities. Random sampling with upweighting of hard-to-reach populations may also provide a solution to achieve a representative population of patients undergoing shoulder arthroplasty.