Urinary HPV Testing for Presence of Cervical HPV
Figure 1 summarises the identification and selection of studies. Of the 1373 potential records, 23 articles reporting on 21 studies (2277 sexually active women) were included in the systematic review. Of these, 16 articles reporting on 14 studies (1535 women recruited, 1443 women analysed) were included in the meta-analysis.
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Figure 1.
Study selection process
Supplementary Appendix 1 details the characteristics of individual studies. Twelve out of 21 study populations were recruited from gynaecology or colposcopy outpatient clinics and seven from genitourinary medicine or HIV clinics. For most study populations the purpose of testing was for cervical cancer screening (15/21). The remainder were for HPV surveillance (5/21) or follow-up of CIN (1/21). Four out of the 21 populations were positive for HIV. Of the 11 populations with reported cytology results, 35.9% (304/847) of women had low grade dysplasia or worse. Of the 10 populations with reported biopsy results, 54.1% (385/712) of women had grade 2 or worse CIN and 17.0% (121/712) had biopsy proved cervical cancer. Most of the studies used conventional PCR (18/21), but testing methods were not uniform. Two of the 21 studies used nested PCR and one out of the 21 used PCR based DNA microarray. Three studies evaluated quantitative real time PCR and hybrid capture in addition to conventional PCR. In these cases, only the results for conventional PCR were included in the meta-analysis. The majority of urine sampling was first void (12/21). Other sampling methods included random (2/21), midstream (2/21), morning (1/21), and not specified (4/21). Urine storage temperature ranged from -70°C to 4°C. Sixteen studies used commercial DNA extraction kits and 11 used commercial amplification platforms. The remainder used in-house methods. The reference standard in all studies was a cervical sample taken by a clinician to test for HPV DNA.
Figure 2 outlines the quality assessment of studies included in the meta-analysis. All included studies avoided case-control designs and most studies (9/14) used consecutive or random recruitment of participants. Six studies had a high risk of bias for patient selection owing to narrow patient spectrums: four articles reported on three studies of only patients with HIV, two studies reported on only adolescents, and one study reported on only patients with high grade CIN. All studies had a low risk of bias owing to patient flow and timing; 13/14 analysed all recruited participants and one analysed 94% of recruited participants. There was an appropriate interval between tests, with 8/14 studies completing both tests on the same day and urine samples being taken before cervical samples. All studies had a low risk of bias for the conduct of the reference standard. Five of the 14 studies used in-house methods for the index test and did not specify a threshold. These were rated as having an unclear risk of bias. The remainder was rated as low risk of bias as they used a prespecified index test threshold (9/14). Only one study reported blinding to test results, although DNA testing is objective and should not result in bias. Regarding applicability of studies to the review questions, there were no concerns about the index test or reference standard. Most studies (19/21) were rated as low concern of applicability for patient selection to the review question. The two rated as having high concerns were studies of adolescents only, because they included patients who would not normally be screened. We found no significant asymmetry in the funnel plot (P=0.62) and hence no evidence of publication bias.
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Figure 2.
QUADAS-2 quality assessment of 14 studies included in meta-analysis
Supplementary Appendix 2(a-c) illustrates the variation in sensitivity and specificity between individual studies for urine detection of any HPV (14 studies), high risk HPV (11 studies), and HPV 16 and 18 (11 studies). For urine detection of any HPV, individual sensitivities ranged from 53% to 99% and specificities from 38% to 99%. For urine detection of high risk HPV, individual sensitivities ranged from 50% to 98% and specificities from 17% to 99%. For urine detection of HPV 16 and 18, individual sensitivities ranged from 23% to 97% and specificities from 56% to 99%.
Figure 3 summarises the pooled sensitivity and specificities as summary receiver operating curves for the same three groups. Urine detection of any HPV had a pooled sensitivity of 87% (95% confidence interval 78% to 92%) and specificity of 94% (95% confidence interval 82% to 98%). Urine detection of high risk HPV had a pooled sensitivity of 77% (68% to 84%) and specificity of 88% (58% to 97%). Urine detection of HPV 16 and 18 had a pooled sensitivity of 73% (56% to 86%) and specificity of 98% (91% to 100%). The 95% prediction regions consistently occupy the whole upper left quadrant of the receiver operating characteristic plots in Figure 3. This demonstrates high heterogeneity between studies. For detection of HPV 16 and 18, the 95% prediction region has the most heterogeneity, occupying most of the plot in Figure 3. Between study variance in specificity (6.0, 95% confidence interval 1.8 to 19.7) was higher when detecting high risk HPV compared with variance in sensitivity (0.4, 95% confidence interval 0.1 to 2.2, Fig 3). For detection of any HPV, the positive likelihood ratio was 15.22 (95% confidence interval 4.56 to 50.81) and the negative likelihood ratio was 0.14 (95% confidence interval 0.10 to 0.20). For detection of high risk HPV, the positive likelihood ratio was 6.33 (1.48 to 27.00) and the negative likelihood ratio was 0.26 (0.16 to 0.41). For detection of HPV 16 and 18, the positive likelihood ratio was 36.97 (6.77 to 201.91) and the negative likelihood ratio was 0.27 (0.15 to 0.49).
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Figure 3.
Receiver operating characteristic plots for studies evaluating accuracy of detecting human papillomavirus (HPV) in urine compared with in cervix
The Table summarises the results of the bivariate metaregression based on planned covariates. There was a 22-fold increase in overall accuracy when samples were collected as first void urine compared with random or midstream urine samples (relative diagnostic odds ratio 21.7, 95% confidence interval 1.3 to 376). However, this difference in accuracy is exclusively based on a significant increase in sensitivity of first void urine (relative sensitivity 1.2, 95% confidence interval 1.06 to 1.37, P=0.004). Specificity was not affected by the urine sampling method (P=0.46). Purpose of testing, mean age of participants, HIV status, cytology and biopsy results, detection methods, use of commercial methods, or risk of bias as a result of patient selection did not explain any heterogeneity between indices for study accuracy.
Pooled sensitivity and specificity for detection of any HPV in urine was similar when studies with a narrow spectrum of patients were excluded. Sensitivity was 80% (95% confidence interval 71% to 88%) and specificity was 98% (95% confidence interval 89% to 100%).
Results
Figure 1 summarises the identification and selection of studies. Of the 1373 potential records, 23 articles reporting on 21 studies (2277 sexually active women) were included in the systematic review. Of these, 16 articles reporting on 14 studies (1535 women recruited, 1443 women analysed) were included in the meta-analysis.
(Enlarge Image)
Figure 1.
Study selection process
Description of Studies
Supplementary Appendix 1 details the characteristics of individual studies. Twelve out of 21 study populations were recruited from gynaecology or colposcopy outpatient clinics and seven from genitourinary medicine or HIV clinics. For most study populations the purpose of testing was for cervical cancer screening (15/21). The remainder were for HPV surveillance (5/21) or follow-up of CIN (1/21). Four out of the 21 populations were positive for HIV. Of the 11 populations with reported cytology results, 35.9% (304/847) of women had low grade dysplasia or worse. Of the 10 populations with reported biopsy results, 54.1% (385/712) of women had grade 2 or worse CIN and 17.0% (121/712) had biopsy proved cervical cancer. Most of the studies used conventional PCR (18/21), but testing methods were not uniform. Two of the 21 studies used nested PCR and one out of the 21 used PCR based DNA microarray. Three studies evaluated quantitative real time PCR and hybrid capture in addition to conventional PCR. In these cases, only the results for conventional PCR were included in the meta-analysis. The majority of urine sampling was first void (12/21). Other sampling methods included random (2/21), midstream (2/21), morning (1/21), and not specified (4/21). Urine storage temperature ranged from -70°C to 4°C. Sixteen studies used commercial DNA extraction kits and 11 used commercial amplification platforms. The remainder used in-house methods. The reference standard in all studies was a cervical sample taken by a clinician to test for HPV DNA.
Quality of Studies
Figure 2 outlines the quality assessment of studies included in the meta-analysis. All included studies avoided case-control designs and most studies (9/14) used consecutive or random recruitment of participants. Six studies had a high risk of bias for patient selection owing to narrow patient spectrums: four articles reported on three studies of only patients with HIV, two studies reported on only adolescents, and one study reported on only patients with high grade CIN. All studies had a low risk of bias owing to patient flow and timing; 13/14 analysed all recruited participants and one analysed 94% of recruited participants. There was an appropriate interval between tests, with 8/14 studies completing both tests on the same day and urine samples being taken before cervical samples. All studies had a low risk of bias for the conduct of the reference standard. Five of the 14 studies used in-house methods for the index test and did not specify a threshold. These were rated as having an unclear risk of bias. The remainder was rated as low risk of bias as they used a prespecified index test threshold (9/14). Only one study reported blinding to test results, although DNA testing is objective and should not result in bias. Regarding applicability of studies to the review questions, there were no concerns about the index test or reference standard. Most studies (19/21) were rated as low concern of applicability for patient selection to the review question. The two rated as having high concerns were studies of adolescents only, because they included patients who would not normally be screened. We found no significant asymmetry in the funnel plot (P=0.62) and hence no evidence of publication bias.
(Enlarge Image)
Figure 2.
QUADAS-2 quality assessment of 14 studies included in meta-analysis
Meta-analysis
Supplementary Appendix 2(a-c) illustrates the variation in sensitivity and specificity between individual studies for urine detection of any HPV (14 studies), high risk HPV (11 studies), and HPV 16 and 18 (11 studies). For urine detection of any HPV, individual sensitivities ranged from 53% to 99% and specificities from 38% to 99%. For urine detection of high risk HPV, individual sensitivities ranged from 50% to 98% and specificities from 17% to 99%. For urine detection of HPV 16 and 18, individual sensitivities ranged from 23% to 97% and specificities from 56% to 99%.
Figure 3 summarises the pooled sensitivity and specificities as summary receiver operating curves for the same three groups. Urine detection of any HPV had a pooled sensitivity of 87% (95% confidence interval 78% to 92%) and specificity of 94% (95% confidence interval 82% to 98%). Urine detection of high risk HPV had a pooled sensitivity of 77% (68% to 84%) and specificity of 88% (58% to 97%). Urine detection of HPV 16 and 18 had a pooled sensitivity of 73% (56% to 86%) and specificity of 98% (91% to 100%). The 95% prediction regions consistently occupy the whole upper left quadrant of the receiver operating characteristic plots in Figure 3. This demonstrates high heterogeneity between studies. For detection of HPV 16 and 18, the 95% prediction region has the most heterogeneity, occupying most of the plot in Figure 3. Between study variance in specificity (6.0, 95% confidence interval 1.8 to 19.7) was higher when detecting high risk HPV compared with variance in sensitivity (0.4, 95% confidence interval 0.1 to 2.2, Fig 3). For detection of any HPV, the positive likelihood ratio was 15.22 (95% confidence interval 4.56 to 50.81) and the negative likelihood ratio was 0.14 (95% confidence interval 0.10 to 0.20). For detection of high risk HPV, the positive likelihood ratio was 6.33 (1.48 to 27.00) and the negative likelihood ratio was 0.26 (0.16 to 0.41). For detection of HPV 16 and 18, the positive likelihood ratio was 36.97 (6.77 to 201.91) and the negative likelihood ratio was 0.27 (0.15 to 0.49).
(Enlarge Image)
Figure 3.
Receiver operating characteristic plots for studies evaluating accuracy of detecting human papillomavirus (HPV) in urine compared with in cervix
Sources of Heterogeneity
The Table summarises the results of the bivariate metaregression based on planned covariates. There was a 22-fold increase in overall accuracy when samples were collected as first void urine compared with random or midstream urine samples (relative diagnostic odds ratio 21.7, 95% confidence interval 1.3 to 376). However, this difference in accuracy is exclusively based on a significant increase in sensitivity of first void urine (relative sensitivity 1.2, 95% confidence interval 1.06 to 1.37, P=0.004). Specificity was not affected by the urine sampling method (P=0.46). Purpose of testing, mean age of participants, HIV status, cytology and biopsy results, detection methods, use of commercial methods, or risk of bias as a result of patient selection did not explain any heterogeneity between indices for study accuracy.
Sensitivity Analysis
Pooled sensitivity and specificity for detection of any HPV in urine was similar when studies with a narrow spectrum of patients were excluded. Sensitivity was 80% (95% confidence interval 71% to 88%) and specificity was 98% (95% confidence interval 89% to 100%).
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