Remote diagnosis of cervical neoplasia: 2 types of telecolposcopy compared with cervicography

The available sample sizes for all analyses were adequate to ensure approximate normality of the estimated means. Power to detect, at Α=.05, a difference in agreement of 15% between cervigram and the other evaluation methods, was estimated using Monte Carlo simulations. Data were simulated using the observed levels of agreement for on-site, network, and computer telecolposcopy, and specifying a difference of 15% between cervicography agreement and the maximum of the other methods’ agreement. Power estimates were based on analysis of 1000 simulations. SAS release 8.02 was used for all calculations (SAS, Inc, Cary, NC).

Results

A total of 264 subjects were enrolled in the trial, but the total number of subjects considered differed depending on the various analyses of interest. The demographic data of this study cohort have been published previously.¹

Briefly, the subjects’ mean age was 31.7 years and mean parity was 2.1. Subjects presented with a wide range of prior cervical cytology results: 20.4% normal, 29.2% atypical squamous cells of undetermined significance, 40.4% low-grade squamous intraepithelial lesion, 7.3% high-grade squamous intraepithelial lesion, and 2.7% atypical glandular cells of undetermined significance. Histology results included all levels of CIN (52.9% CIN 1 and 13.4% CIN 2 or 3), and endocervical histologic sampling results were reported as both positive and negative for neoplasia.

The agreement between telecolposcopic/cervicography impressions and histology were estimated (Table 1). Data for on-site colposcopy was also considered for reference purposes.

When all histologic diagnoses were considered, there was no statistically significant difference in the rates of agreement for colposcopy, the 2 types of telecolposcopy, and cervicography. This was also true if only cases of CIN 1 were examined.

However, a statistically significant difference was noted between agreement rates for computer-based telecolposcopy (63.95%) and on-site colposcopy (47.7%, P=.03, Tukey test) for normal histology. A statistically significant difference was also found between agreement rates for on-site colposcopy (50.0%) and cervicography (19.1%, P=.04, Tukey test) for women with biopsy-proven CIN 2 or 3. If all histologic diagnoses were considered, the study provided 85% power to detect a difference in agreement of 15% among the evaluation methods.

We also estimated the sensitivity and specificity of the four diagnostic methods to detect cervical neoplasia (Table 2). A statistically significant difference was found in observed sensitivity between on-site colposcopy (47.7%) and cervicography (18.2%, P=.04, Tukey test) when a positive threshold of at least CIN 2 was considered. The difference was not significant, however, if the lower positive test threshold of at least CIN 1 was considered.

A statistically significant difference in specificity was noted between computer-based telecolposcopy (64.0%) and on-site colposcopy (47.7%, P=.03, Tukey test) at a positive threshold of at least CIN 1. The study provided a power of 71% and 60% to detect differences of 15% in sensitivity and specificity, respectively, using the CIN 1 threshold. Using CIN 2 as the positive threshold, the power to detect this 15% difference was 24% and 81% for sensitivity and specificity, respectively.

TABLE 1
Colposcopic, telecolposcopic, and cervicographic agreement with histology

TABLE 2
Sensitivity and specificity of tests to detect cervical neoplasia