Responsiveness and construct validity of a symptom scale for acute otitis media.

BACKGROUND Because resolution of symptoms is a primary goal of antimicrobial therapy in children with acute otitis media (AOM), measurement of symptoms in studies of antimicrobial effectiveness in such children is important. We have developed a scale for measuring symptoms of AOM in young children (AOM-SOS), and we present data on its construct validity and responsiveness. METHODS We followed children 3 months to 3 years of age with AOM, who were receiving antimicrobial treatment, using the AOM-SOS scale. The scale was administered at the enrollment visit, as a twice-a-day diary measure, and at the follow-up visit (days 5-7). To evaluate construct validity, we examined the correlation, at entry, between AOM-SOS scores and scores on other measures of pain and functional status. To evaluate the scale's responsiveness, we examined the change in scale scores from entry to follow-up. We also examined the levels of agreement between the scale scores and overall assessments of the children by parents. RESULTS We enrolled 70 children (mean age 12.5 months) of whom 57 returned for follow-up. The magnitude of the correlations between the AOM-SOS scale scores and other measures of pain and functional status ranged from 0.56 to 0.84. The responsiveness of the AOM-SOS, as measured by the standardized response mean was 1.20. CONCLUSIONS These data support the validity and responsiveness of the AOM-SOS; the scale seems to measure effectively both pain and overall functional status in young children with AOM. Changes in score over the first few days of illness were substantial and generally matched the assessments both of parents and of clinicians. The AOM-SOS promises to be useful as an outcome measure in clinical studies of AOM.