[Correlation between subjective and objective health measurements in patients with chronic obstructive pulmonary disease (COPD)].

AIMS

Analyze the relation between objective health assessment (OHA) -Forced spirometry- and subjective health assessment (SHA) -quality of life- in patients with chronic obstructive pulmonary disease (COPD). Analyze the correlation between two different questionnaires to assess quality of life.

DESIGN

Cross-sectional study.

PARTICIPANTS

278 patients with COPD (confidence level 95%) from two urban health centers.

MAIN MEASUREMENTS

Personal interview.

VARIABLES

quality of life (Nottingham Health Profile; St George Respiratory Questionnaire); sociodemographic profile; diagnose of COPD; comorbidity; recent spirometry.

STATISTICAL ANALYSES

Descriptive statistics; test ji-squared, Kruskal-Wallis and the correlation coefficient.

RESULTS

Age: 66,9 years; sex: 88% male. Quality of life scales (mean and confidence intervals): Nottingham Health Profile subscales (total score 100 points): energy 40 (35.6-44.4), pain 35.9 (32.3-39.5), emotional reactions 32.5 (29.4-38.6), sleep 41.9 (37.8-45.9), social isolation 15.3 (12.7-17.9), mobility 36.7 (33.9-39.5) and global score 33.4 (30.8-36). St George Respiratory Questionnaire subscales (total scores 100 points): impact 38.01 (35.08-40.18), activity 53.8 (50.2-57.4), symptoms 37.7 (35.2-40.3) and global score 40.0 (38.6-43.2). The correlation coefficients between the two questionnaires ranged between 0.12 (for the sleep and symptoms dimensions: p = 0.03) and 0.66 (for the mobility and activity dimensions; p < 0.0001). There is a positive lineal relation between the two questionnaires and the spirometric stages of COPD (measured by the maximum respiratory volume in the first second).

CONCLUSIONS

We found a good correlation between the two quality of life questionnaires, but St George was more specific for respiratory illness. There is a mild-light correlation between objective and subjective health assessment in patients with COPD.