She described viral load testing practices at MSF treatment facilities in Thyolo district, Malawi, and Buhera district, Zimbabwe. Both sites have implemented routine viral load testing since 2011.
In Buhera, given lack of frequent transport from clinics to the district laboratory and challenges in transporting samples to the capital laboratory using cold chain, dried blood spot (DBS) using EDTA venous blood is used. At the primary healthcare level, nurses collect blood samples. Viral load is first conducted at month three, and then again yearly.
In Thyolo blood for viral load testing is sampled and shipped using dried blood spots. "When you move to dried blood spots, you do lose something on the sensitivity, but we showed that the specificity remained good," said Bygrave, who noted that a systematic review on DBS is soon expected, and that the WHO will give guidance on viral load methods early next year.
While there were concerns from the conference floor about the use of DBS, Bygrave notes that Venus DBS is "well validated in many countries," and that in many resource-constrained settings, "without DBS, getting viral load done anywhere outside of central hospitals is not possible. The reality of scaling up viral load in rural settings without DBS - I simply don't see it, given the challenges with sample transport."
In Malawi, MSF is currently considering outcomes when sample preparation is shifted to lay workers. Viral load is first conducted at month six, and then again twice yearly.
In order to reduce costs, the project utilised "viral load pooling," which includes testing five DBS samples together: if a result comes back negative (that is, below 1,000 copies/mL), then it can be assumed that all of the patients have a viral load below 1,000 copies/mL. If it comes back positive, then, using an algorithm, all patients undergo further viral load testing. Bygrave says that this method reduced the number of viral load tests required by 30%, saving the district up to $207,000 a year. The Ministry of Health is now considering using this method nationally.
Bygrave notes that rolling out viral load testing does not happen overnight: although a concerted effort to scale-up viral load started in Zimbabwe in 2010, a scale-up wasn't seen until 2012. In Buhera, after 24 months of using DBS, 83% of the cohort had a viral load result. In Thyolo, after 24 months, only 27% of the cohort had a viral load result. Of those having a first routine viral load test in 2012, 12.6% in Buhera and 7.1% in Thyolo had a viral load above 1,000 copies/mL. Bygrave notes that implementing viral load may negate the need for CD4 monitoring. In Zimbabwe, CD4 monitoring was stopped; in Malawi, it was never started.
Bygrave says that simply conducting a viral load test isn't enough. She observes a "viral load cascade," in which patients are lost between getting a viral load test, receiving follow up care, getting a second viral load, and being switched to second line treatment if needed. "Viral load is not a magic bullet, and unless we supervise this algorithm, it's not going to work…We have to get results to patients, and we have to be very sure about supervision of this cascade so that we don't pour a lot of money down the drain to implement a new test that's not going to be acted on."
Of those in Zimbabwe whose viral load remained high despite enhanced adherence counselling, only a little over 50% were switched to second line. Bygrave notes that decision making about switching patient's regimens is "highly centralised" and doctor-oriented in most countries, and that there are concerns over switching patients to more expensive second line treatment if they are considered to have poor adherence.
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