Correlation between the SF-36 and CCVUQ Quality of Life Scales, Applied to Patients with Venous Ulcers: a cross-sectional study carried out in primary health care in Brazil

This study aimed to analyze the correlation between the QL scales SF-36 and CCVUQ, applied to people with VU assisted in Brazilian PHC units. This is an observational, cross-sectional study with a quantitative approach, carried out in 2020 in a center specialized in the prevention and treatment of chronic VU, which is a reference service for 29 PHC units in the city of Parnamirim, state from Rio Grande do Norte, Brazil. The study population consisted of patients who had active VU, treated at the PHC in the city of Parnamirim, which is located in the metropolitan region of the city of Natal, capital of the state of Rio Grande do Norte. We used the SF-36, which assesses eight domains and two dimensions of QoL, and the CCVUQ, a specific questionnaire to assess QoL in individuals with VU, which identifies four important divisions of health. To assess the internal consistency of the QoL scales (SF-36 and CCVUQ), we performed Cronbach's inferential analysis (α), using the following parameters: 0.30 < α ≤ 0.60 (low); 0.60 < α ≤ 0.75 (moderate); 0.75 < α ≤ 0.90 (high); α > 0.90 (very high). To analyze the correlation (r) between the scalar variables of both scales, the Spearman Rho Test was used. Their classification according to the levels of correlation was determined by the following parameters: r < 0.29 (weak); 0.29 > r < 0.49 (moderate); r > 0.50 (strong). The direction of the correlation was classified considering that the SF-36 scale indicates better QoL when it results in higher scores (increasing direction for better QoL), while the CCVUQ scale presents a decreasing sense to determine better QoL. Therefore, we called it “direct correlation” when r was negative and “opposite correlation” when r was positive. For all tests, we adopted a margin of error of 5% and a Confidence Interval (CI) of 95%, with a significance value of p