Influence of Pain on the Quality of Life of Patients with Venous Ulcers: Cross-sectional Association and Correlation Study in Primary Health Care

This study aimed to verify the association and correlation between pain and QoL in people with VU assisted in Brazilian PHC. Descriptive, observational, cross-sectional study with a quantitative approach, carried out from August to October 2019, with patients treated at the PHC in the municipality of Parnamirim, State of Rio Grande do Norte, Brazil. The city has 29 Basic Health Units (UBS) distributed among the 23 neighborhoods of the city, which has a population of 272,490 inhabitants and is located in the Metropolitan Region of Natal, the state capital. Before data collection, each health unit was previously visited to obtain the total number of people with VU treated, which totaled 157 patients. Based on this quantity, the sample calculation was performed using an online formula of quantitative variables for finite populations (https://calculareconverter.com.br/calculo-amostral/). A population size of 157 was considered, with a confidence level of 95% and a margin of error of 5%, resulting in 112 individuals. All units could be consulted and the final sample had representatives from all UBS. A total of 103 individuals who were located and surveyed completed the study. The Short Form Health Survey 36 (SF-36) and the Visual Analog Pain Scale (VAPS) were used. Data collection took place in the form of face-to-face interviews during consultations in the office of the specialized service in VU treatment and were guided by the questions of the selected instruments. For nominal variables, the normality test (Kolmogorov-Smirnov) was applied, identifying a non-normal sample. For sample characterization, absolute (n) and relative (%) frequencies were used. Pearson's non-parametric chi-square test was used to assess the association between sample characteristics and the presence of ulcers, and the percentiles with the SF-36 domains and dimensions. The Kruskal-Walis test was used to assess the association between the domains and dimensions of the SF-36 instrument and the pain scale, and the Spearman Rho test was used to assess the correlation (r) between these scalar variables of pain and QOL . In the correlation analysis, we adopted the following parameters to classify the correlation strength: weak &lt;0.39, moderate between 0.40 and 0.50, and strong correlation &gt;0.50. By Cronbach's α test, the SF-36 was evaluated with good internal consistency, due to α=0.78, in which values greater than 0.70 reveal good consistency. For all tests, we considered a 5% margin of error, a 95% Confidence Interval (CI) and a statistical significance value when p&lt;0.05. 103 patients participated in the study. Higher QoL scores associated with moderate pain were found, especially in the Physical role functioning, Physical functioning and Vitality domains. The correlation analysis pointed out its greater strength (moderate) in the interaction between the highest scores in the Physical role functioning and Emotional role functioning domains and the lowest pain levels.本研究旨在验证巴西初级卫生保健（Primary Health Care, PHC）机构服务的静脉性溃疡（Venous Ulcer, VU）患者中，疼痛与生活质量（Quality of Life, QoL）之间的关联及相关性。本研究为描述性观察性横断面研究，采用定量研究方法，于2019年8月至10月在巴西北里奥格兰德州帕尔纳里姆市的初级卫生保健机构开展，研究对象为该市初级卫生保健机构接诊的静脉性溃疡患者。该市下辖23个街区，共设有29所基础卫生保健单元（Basic Health Units, UBS），总人口272490人，地处州府纳塔尔大都会区。数据收集前，研究团队先行走访各卫生单元，统计接诊的静脉性溃疡患者总人数，共计157例。基于该总体量，采用针对有限总体的定量变量样本量计算公式（https://calculareconverter.com.br/calculo-amostral/）进行样本量估算，设定总体量为157、置信水平95%、误差边际5%，最终计算得出所需样本量为112例。所有卫生单元均可纳入调研，最终样本覆盖全部基础卫生保健单元。最终共有103名成功联系并完成调研的受试者参与本研究。本研究采用健康调查简表36（Short Form Health Survey 36, SF-36）与视觉模拟疼痛量表（Visual Analog Pain Scale, VAPS）进行数据采集。数据采集于静脉性溃疡治疗专科门诊的就诊期间，采用面对面访谈形式，由研究人员严格按照所选量表的指导语及条目开展访谈。对于名义变量，采用柯尔莫哥洛夫-斯米尔诺夫（Kolmogorov-Smirnov）正态性检验，结果显示样本不符合正态分布。样本特征描述采用绝对数（n）与相对数（%）进行表述。采用非参数皮尔逊卡方检验评估样本特征与溃疡存在情况的关联，以及健康调查简表36各领域与维度的百分位数分布。采用克拉斯卡-沃利斯（Kruskal-Wallis）检验评估健康调查简表36各领域、维度与疼痛量表的关联；采用斯皮尔曼rho（Spearman Rho）检验评估疼痛与生活质量这两个计量变量间的相关系数（r）。在相关性分析中，本研究采用以下标准对关联强度进行分级：弱相关<0.39，中度相关0.40~0.50，强相关>0.50。通过克朗巴赫α（Cronbach's α）系数检验评估健康调查简表36的内部一致性，结果显示α=0.78，因α值大于0.70，表明该量表具有良好的内部一致性。所有统计检验均设定5%的误差边际、95%置信区间（Confidence Interval, CI），并以p<0.05作为统计学显著性的判定标准。本研究共纳入103例患者。结果显示，生活质量评分较高的患者往往伴随中度疼痛，该特征在躯体角色功能、躯体功能与活力领域尤为显著。相关性分析结果表明，躯体角色功能与情绪角色功能领域得分最高者，其疼痛水平最低，二者间的关联强度为中度相关。