Cost-effectiveness of Screening Program for Chronic Q Fever, the Netherlands

Abstract

C hronic Q fever (CQF) is a potentially lethal condition that develops in 2% of Q fever (QF) patients (1). QF is caused by infection with Coxiella burnetii, a gram-negative bacterium that has its main reservoir in livestock and can infect humans by airborne transmission. CQF can become apparent months to years after infection and usually manifests as endocarditis or vascular infection (2). Risk factors for CQF include heart valve disorders, aortic aneurysms, vascular prostheses, older age, and a compromised immune system (3-5). Prognosis is poor despite long-term antimicrobial drug treatment; 28% of patients need surgery, and 15% die from CQF-related complications (6). During 2007-2010, the Netherlands faced the world's largest QF epidemic ever documented. More than 4,000 patients with acute QF were notified. However, QF often occurs asymptomatically (1), and the total number of infections has been estimated at 50,000 (7). Through May 2016, a substantial number of CQF infections occurred, and at least 74 patients died (8). Because early detection of CQF might result in a better prognosis, local hospitals initiated multiple targeted screening studies for clinical risk groups living in areas affected by the epidemic. These studies revealed that 7%-20% of screened patients had serologic evidence of C. burnetii infection, of whom 5%-31% had CQF (9-11). In 2017, new diagnoses of CQF continued to appear in the Netherlands, often with severe complications, and led to a call from multiple concerned parties, including politicians, the QF patient association, and medical doctors for a national CQF screening program. One aspect considered for such a screening program is whether its costs are economically balanced with the expenditure (12,13). To answer this question, we assessed the cost-effectiveness of a screening program for CQF in the Netherlands. Methods Overview We developed a health-economic decision model to compare estimated costs and effects of a 1-time screening program for CQF with no such screening program (Figure 1). The screening was assumed to occur in 2017, seven years after the epidemic. We estimated comparative outcomes of the model in terms of clinical events, quality-adjusted life years (QALYs), and costs from a societal perspective. We used a lifetime time horizon. Costs were annually discounted at 4% and QALYs at 1.5% (14).

Development of High-Throughput Multiplex Serology to Detect Serum Antibodies against Coxiella burnetii

“…There is particular interest in large-scale studies to examine the role of C. burnetii. For this purpose, accurate and cost-effective high-throughput methods are desirable [10,14].…”

“…The generation of IFAs, however, requires biosafety level 3 conditions, making it laborious and cost-intensive [22]. Furthermore, the assay conduct is non-automated and, therefore, not suitable for large-scale studies [14]. Hence, multiple approaches to substitute IFAs have been conducted.…”

Long-term serological follow-up after primary Coxiella burnetii infection in patients with vascular risk factors for chronic Q fever

“…In screening programs performed earlier after the outbreak, the percentage of high-risk patients with unknown serological status that were diagnosed with chronic Q fever was higher (1.6–4.2%) [ 6 , 12 ]. Currently, a nationwide case finding program is being performed in high-risk patients in the Netherlands after this program was expected to be cost-effective [ 13 ].…”

Targeted Screening for Chronic Q Fever, the Netherlands

“…We calculated seroprevalence per general practitioner, as well as the number and percentage of suspected chronic Q fever patients per general practitioner. Previously, a health-economic decision model was developed to estimate the cost-effectiveness of the screening program ( 8 ). Results collected in our study were used to update the cost-effectiveness analysis.…”

“…Identifying these undiagnosed patients can provide major health benefits by reducing complications and deaths. A recent model-based study from the Netherlands estimated that targeted screening of patients who had risk factors in regions that had previous outbreaks, was cost-effective ( 8 ). After a strong appeal from Q fever patients and the involved physicians, a screening program was launched in the Netherlands 10 years after the Q fever outbreak.…”