The careHPV™ Test is US FDA approved, CE mark, and WHO prequalified in vitro diagnostic test that has been extensively evaluated in numerous countries such as China (23), Thailand (16) Nigeria (24), India (25), and Ghana (26). The careHPV™ Test has a sensitivity of 87.76%; CI = 81.69–92.34% and a specificity of 85.37%; CI = 83.19–87.38% in detecting HRHPV infection, which correlates to CIN2 or worse. It has a positive predictive value (PPV) and negative predictive value (NPV) of 44.64% and 98.11%, respectively. The lower PPV may be attributed to the prevalence of HRHPV in a population as values decrease when testing populations with low prevalence or individuals with no risk of infections.
Most literature on the use of careHPV had described the permanent installation of their careHPV™ instruments in the established public healthcare facilities serving a high-density population such as in Drum Tower Hospital, Nanjing, China (27) within the second largest city in China, Moi Teaching and Referral Hospital, Eldoret, Kenya (28) the largest referral hospital in West Kenya, Barretos Cancer Hospital (BCH), Barretos, São Paulo, Brazil(29), Maternal and Child Health Hospital in Bachu County, Xinjiang, China(30), and the Institute of Cytology and Preventive Oncology, Uttar Pradesh, India(25) outskirt of New Delhi. They have used the opportunistic sampling method, recruiting patients attending their facilities for consultation that may not be related to cervical cancer. Therefore, the collection of a sufficient number of specimens for a complete batch-test during the recommended storage period may not be a matter of concern. However, our targeted population in rural Sarawak is of low-density and may not readily have access to proper healthcare facilities whereby bringing healthcare to them through medical outreach programmes may be the best option.
The careHPV™ Test protocol involves seven manual stages offering a realistic turnaround time of 3 hours. Despite its robust design, the careHPV™ Test System cannot tolerate power interruption. It will reboot itself back to the first stage, a default response that effectively voids the batch and wastes the careHPV™ Test Kit(16). Nevertheless, the high repeatability of samples in the careHPV™ Collection Medium allows storage, further consolidation and retest at a future date to be carried out with confidence. Furthermore, samples with confirmed results can be used as positive and negative in-house controls.
This manuscript mainly discusses the extended stability of samples in storage for the benefit of consolidation in order to achieve the economy of a full batch test. However, the careHPV™ Test Kit with a lower capacity of 18 samples per batch in 24-well format is available (17) and would be ideal to be used as the primary cervical cancer screening method in the low-density population such as in Sarawak. However, the 24-well format is not available in Malaysia at the time of writing.
Although the repeatability of the results shown using a small number of verified samples is high, we do not recommend prolonged storage of untested samples beyond the manufacturer's recommendation as delayed results may not have a significant clinical benefit for women. However, in an unforeseen event where stored samples are tested outside the recommended storage duration, such as during the laboratory shut down due to the coronavirus disease-19 pandemic may still be valid if resampling is not feasible.