There are difficulties in carrying out research in low-income urban communities, but the methodological challenges and suggestions on how to deal with them are often undocumented. The aims of this study are to describe the challenges of recruiting and enrolling low-income pregnant women with periodontitis to a clinical trial on vitamin D/calcium milk fortification and periodontal therapy and also to describe the patient-, study protocol- and setting-related factors related to women’s ineligibility and refusal to participate in the study. A mixed-method sequential exploratory design was applied. Qualitative and quantitative data on recruitment to a 2 × 2 factorial feasibility clinical trial were used. Eighteen women attending the health centre in a low-income area in Duque de Caxias (Rio de Janeiro, Brazil) took part in focus group discussions, and the data were thematically analysed. Quantitative data were analysed using appropriate descriptive statistics, including absolute and relative frequencies. Of all referrals (767), 548 (78.5%) did not meet the initial eligibility criteria. The main reason for exclusion (58%) was advanced gestational age (> 20 weeks) at first prenatal appointment. In the periodontal examination (dental screen), the main reason for exclusion was the presence of extensive caries (64 out of 127 exclusions). Non-participation of those eligible after the periodontal examination was approximately 24% (22 out 92 eligible women) and predominantly associated with patient-related barriers (e.g. transportation barriers, family obligations, patients being unresponsive to phone calls and disconnected telephones). The study recruited 70 women with periodontitis in 53 weeks and did not reach the benchmark of 120 women in 36 weeks (58.3% of the original target). Recruitment was severely hindered by health centre closures due to general strikes. The recruitment yields were 9.1% (70/767) of all women contacted at first prenatal visit and 76.1% (70/92) of those screened eligible and enrolled in the trial. Women did not report concerns regarding random allocation and considered fortified milk as a healthful and safe food for pregnant women. Some women reported that financial constraints (e.g. transportation costs) could hinder participation in the study. Engagement between the research team and health centre staff (e.g. nurses) facilitated referral and recruitment, yet some pregnant women failed to participate in the study largely due to significant patient-related sociodemographic barriers and setting-related factors. Our data illustrate the complexity of overcoming recruitment and enrolment challenges for clinical trials in resource-limited settings. ClinicalTrials.gov, NCT03148483. Registered on 11 May 2017.

中文翻译：

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招募低收入孕妇进行饮食和牙科护理干预：可行性试验的经验教训

在低收入城市社区开展研究存在困难，但方法上的挑战和如何应对这些挑战的建议往往没有记录。本研究的目的是描述招募和招募患有牙周炎的低收入孕妇参加维生素 D/钙奶强化和牙周治疗临床试验的挑战，并描述患者、研究方案和环境相关的与妇女没有资格和拒绝参加研究有关的因素。应用了混合方法序贯探索性设计。使用了 2 × 2 析因可行性临床试验招募的定性和定量数据。在 Duque de Caxias（巴西里约热内卢）低收入地区卫生中心就诊的 18 名妇女参加了焦点小组讨论，并对数据进行了专题分析。使用适当的描述性统计分析定量数据，包括绝对频率和相对频率。在所有推荐 (767) 中，548 (78.5%) 不符合初始资格标准。排除的主要原因 (58%) 是第一次产前预约时孕龄较高（> 20 周）。在牙周检查（牙科筛查）中，排除的主要原因是存在广泛的龋齿（127 例排除中的 64 例）。符合条件的人在牙周检查后未参加的比例约为 24%（92 名符合条件的女性中有 22 人），主要与患者相关的障碍（例如交通障碍、家庭义务、患者对电话没有反应以及电话断线）有关。该研究在53周内招募了70名患有牙周炎的女性，但没有达到36周内120名女性的基准（原始目标的58.3%）。总罢工导致卫生中心关闭，招募工作受到严重阻碍。第一次产前检查时接触的所有女性的招募率为 9.1% (70/767)，筛选合格并参加试验的女性的招募率为 76.1% (70/92)。妇女没有报告对随机分配的担忧，并认为强化牛奶是孕妇健康、安全的食品。一些妇女报告说，经济限制（例如交通费用）可能会阻碍参与研究。研究团队和健康中心工作人员（例如护士）之间的互动促进了转诊和招募，但一些孕妇未能参与研究，主要是由于与患者相关的社会人口统计学障碍和环境相关因素。我们的数据说明了在资源有限的环境中克服临床试验招募和入组挑战的复杂性。ClinicalTrials.gov，NCT03148483。2017 年 5 月 11 日注册。