Urine sampling could potentially become an acceptable alternative to conventional cervical cytology for detecting cervical human papilloma virus (HPV), a systematic review and meta-analysis suggests.

The study authors searched databases including Medline, Embase, Cochrane Library, Web of Science, BIOSIS, DARE and SIGLE for articles relating to the use of urine samples in screening and detection of HPV for cervical cancer in sexually active women. Studies were excluded if they had a high prevalence of HPV, used populations comprising only patients with HIV, cervical cancer, high-grade CIN or whose age was below screening recommendations.

A total of 16 articles reporting on 14 studies, covering 1,443 women, were included in the meta-analysis.

Outcome data from the studies were pooled into a contingency table and a forest plot was used to look at heterogeneity of data across studies.

The authors looked at the sensitivities and specificities of any HPV detection, high-risk HPV, and HPV types 16 and 18, see table 1.

There was a high heterogeneity among studies; regression analysis showed the differences in diagnostic accuracy could not be explained by purpose of testing, mean age of participants, HIV status, cytology and biopsy results, detection methods, use of commercial methods, or risk bias caused by patient selection.

There was a 22-fold increase in overall accuracy in use of first-void urine compared with random or mid-stream samples; this is exclusively based on increased sensitivity of first-void urine samples. The relative sensitivity was 1.2 (95% CI:1.06-1.37; P = 0.004); there were no effects on specificity.

Routine screening using cervical cytology to detect and treat CIN can prevent cancers from progressing. However, despite availability of screening, cervical cancer is still the most common malignancy in women under 35. The coverage of screening in young women is also reducing.

HPV detection is being used as a method of cervical cancer screening. This can be more protective against higher-grade CINs compared with cervical smears. However, the sampling method is still invasive and time consuming and unlikely to improve the poor screening uptake.

Previous studies have shown that detection of urine HPV can be a feasible alternative to cervical sampling.

The authors of this systematic review concluded that where cervical testing for HPV is being considered for cervical cancer screening, urine-based testing can be considered instead as this may be an acceptable alternative to increase coverage for groups that are hard to reach.

The accompanying editorial¹ welcomed the suggestion of using urine HPV testing as a potentially useful self-sampling screening test. However, unlike vaginal self-samples, urine samples have not been evaluated for the detection of CIN – which is the outcome that matters most.

It may be some time before urine or vaginal self-samples can replace current cervical smears as further evaluation comparing urine testing and vaginal self-sampling in the detection of high-grade CIN as the primary endpoint needs to be done.

Until such time, women and clinicians will have to put up with the cumbersome, and for some embarrassing, procedure of cervical smears using speculum examinations.

Dr Richard Ma