Scarcity of Lupus Assays in Developing Countries Limit Utility of International Criteria, Trials
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ATLANTA — Limited access to supportive laboratory assays in developing countries significantly reduces the diagnostic utility of the ACR/EULAR criteria for systemic lupus erythematosus, which relies on an antinuclear antibody titer of 1:80 for its entry criterion, noted a presenter at the 2019 ACR/ARP Annual Meeting.
“We know that a certain percentage of patients with lupus have traditionally not been ANA positive, but this new [ACR/EULAR classification] criteria does a couple of things different — one is that it allows for a point system,” Ashira Blazer, MD, MSCI, of New York University Langone Health and Bellevue Hospital Center, said during a press conference. “Instead of getting one point for one symptom, you might get four points for less serious or less specific symptoms of lupus, or 10 points for more serious or more specific symptoms of lupus. For example, one might be able to garner 10 points for lupus nephritis.”
“These new criteria also introduce an ANA entry criterion, which means that someone must have a positive serologic test for an ANA to gain a diagnosis of lupus by these criteria,” she said. “These are meant to be used for research or academic purposes, but are often used as diagnostic criteria. We wanted to know whether these newly developed criteria performed the same in the developing world as in the developed world.”
To determine whether a criteria disparity exists, Blazer and colleagues collected data on SLE patients from two West African cohorts — Korle bu Teaching Hospital in Accra, Ghana (n=110) and Lagos University Teaching Hospital in Nigeria (n=94) — and compared them with a cohort of patients from NYU Langone (n=151). Among the cohorts, the researchers examined demographics, SLE criteria, Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) scores, Systemic Lupus International Collaborating Clinics (SLICC) damage indexes, vital signs and laboratory values obtained during the patients’ initial encounters.
Additionally, Blazer and colleagues collected longitudinal data over 1 year at 6-month intervals during routine clinical visits, and — when necessary — retrospectively reviewed clinical charts. The researchers then calculated the proportion of patients in each cohort who met ACR, SLICC and ACR/EULAR classification criteria.
According to study results, among the cohort of African American patients from NYU Langone, 96% met the ACR criteria, 96% met the SLICC criteria and 95% met the ACR/EULAR criteria. Comparatively, 85% of the Ghanaian cohort met the ACR criteria and 84% met the SLICC criteria — only 62% met the new ACR/EULAR criteria. Similar results were found in the Nigerian cohort, which showed that although 90% met the ACR criteria and 87% met the SLICC criteria, only 61% met the ACR/EULAR criteria.
“All of the criteria actually performed worse in the Ghanian and Nigerian cohorts than in the African American cohort,” Blazer said. “This may seem a bit counterintuitive, but you have to remember that many people cannot afford to get lab tests, so whereas in the African American cohort, we may give points for double-stranded DNA antibodies or complements, we don’t have that available in these other cohorts.”
The researchers noted that the absence of laboratory data was largely responsible for the discrepancies in the criteria application. Although none of the African American cohort was missing ANA data, 26% of the Ghanian cohort and 33% of the Nigerian cohort lacked this information. Compared to both the Ghanaian and Nigerian cohorts, the African American cohort was more likely to meet ACR (Ghanian=10.2, P< .001; Nigerian=3.0, P=.08) SLICC (Ghanian=11.5, P< .001; Nigerian=6.3, P=.01) and ACR/EULAR (Ghanian=46.1 P< 0.001; Nigerian=44.9, P< 0.001) criteria.
“We found that likelihoods ratios were lowest for the ACR criteria — about 3 in the Ghanian cohort and about 8 in the Nigerian cohort,” Blazer said. “However, for the ACR/EULAR criteria, the likelihoods ratios were 44 for both cohorts; you were 44 times more likely to be diagnosed if you were in developed country than if you were in the Ghanian or Nigerian cohorts.”
Although the reliance on the ANA entry criterion limited the usefulness of the ACR/EULAR criteria for the Ghanian and Nigerian cohorts, the researchers noted that its weighted point system performed better than the ACR or SLICC criteria, with 96% of the African American cohort, 92% of the Ghanaian cohort and 95% of the Nigerian cohorts accruing an adequate number of diagnostic points.
“The important thing to remember is that sometimes when we are making these criteria, we engage the community, and sometimes the international community doesn’t involve people who are experts in the developing world,” Blazer said. “It is important to understand the needs of all sides where there might be lupus patients – there are many lupus patients in West Africa, yet our literature still says there is no lupus in West Africa.”
She noted, “We want to ensure that our research criteria suit those states, so that clinicians or scientists doing research are able to participate in the national discourse. We don’t want to create barriers to care for an area that is already resource-poor and less likely to be able to conduct clinical trials, research or get the diagnosis.”– by Robert Stott
Reference:
Blazer A. Abstract #705. A tale of three cohorts: SLE criteria in developed vs. developing countries. Presented at ACR/ARP Annual Meeting, Nov. 8-13, 2019; Atlanta.
Disclosure: Blazer reports no relevant financial disclosures.