Cost-effectiveness of alternative strategies for tuberculosis screening before kindergarten entry

Valuing Academic Freedom and Advocacy

This is a correspondence letter in response to an article published in the journal: Flaherman VJ, Nankabirwa V, Ginsburg AS. Promoting Transparent and Equitable Discussion of Controversial Research. Journal of Empirical Research on Human Research Ethics 2023; 18(4): 248-9.

Iron deficiency screening for children at 18 months: a cost-utility analysis

BACKGROUND

The peak prevalence of iron deficiency is in children 6 months to 3 years of age, a sensitive period for neurodevelopment. Our study objective was to examine the cost-utility of a proposed iron deficiency screening program for 18-month-old children.

METHODS

We used a decision tree model to estimate the costs in 2019 Canadian dollars and quality-adjusted life years (QALYs) associated with 3 iron deficiency screening strategies: no screening, universal screening and targeted screening for a high-risk population. We used a societal perspective and assessed lifetime QALY gains. We derived outcomes from the literature and prospectively collected data. We performed one-way and probabilistic sensitivity analyses to assess parameter uncertainty.

RESULTS

The incremental costs to society of universal and targeted screening programs compared to no screening were $2286.06/QALY and $1676.94/QALY, respectively. With a willingness-to-pay threshold of $50 000/QALY, both programs were cost-effective. Compared to a targeted screening program, a universal screening program would cost an additional $2965.96 to gain 1 QALY, which renders it a cost-effective option. The study findings were robust to extensive sensitivity analyses.

INTERPRETATION

A proposed universal screening program for iron deficiency would be cost-effective over the lifespan compared to both no screening (current standard of care) and a targeted screening program for children at high risk. Policy-makers and physicians may consider expanding the recommended 18-month enhanced well-baby visit to include screening for iron deficiency.

Recommendations for the screening of paediatric latent tuberculosis infection in indigenous communities: a systematic review of screening strategies among high-risk groups in low-incidence countries

Background

Tuberculosis (TB) continues to be a global public health concern. Due to the presence of multiple risk factors such as poor housing conditions and food insecurity in Canadian Indigenous communities, this population is at particularly high risk of TB infection. Given the challenges of screening for latent TB infection (LTBI) in remote communities, a synthesis of the existing literature regarding current screening strategies among high-risk groups in low-incidence countries is warranted, in order to provide an evidence base for the optimization of paediatric LTBI screening practices in the Canadian Indigenous context.

Methods

A literature search of the Embase and Medline databases was conducted, and studies pertaining the evaluation of screening strategies or screening tools for LTBI in paediatric high-risk groups in low-incidence countries were included. Studies focusing on LTBI screening in Indigenous communities were also included, regardless of whether they focused on a paediatric population. Their results were summarized and discussed in the context of their relevance to screening strategies suitable to the Canadian Indigenous setting. Grey literature sources such as government reports or policy briefs were also consulted.

Results

The initial literature search returned 327 studies, with 266 being excluded after abstract screening, and 36 studies being included in the final review (original research studies: n = 25, review papers or policy recommendations: n = 11). In the examined studies, case identification and cost-effectiveness of universal screening were low in low-incidence countries. Therefore, studies generally recommended targeted screening of high-risk groups in low-incidence countries, however, there remains a lack of consensus regarding cut-offs for the incidence-based screening of high-risk communities, as well as regarding the utility and prioritization of individual risk-factor-based screening of high-risk groups. The utility of the TST compared to IGRAs for LTBI detection in the pediatric population also remains contested.

Conclusions

Relevant strategies for targeted screening in the Canadian Indigenous context include community-level incidence-based screening (screening based on geographic location within high-incidence communities), as well as individual risk-factor-based screening, taking into account pertinent risk factors in Indigenous settings, such as poor housing conditions, malnutrition, contact with an active case, or the presence of relevant co-morbidities, such as renal disease.

Private sector tuberculosis prevention in the US: Characteristics associated with interferon-gamma release assay or tuberculin skin testing

OBJECTIVE

To determine whether latent tuberculosis infection risk factors are associated with an increased likelihood of latent tuberculosis infection testing in the US private healthcare sector.

DATA SOURCE

A national sample of medical and pharmacy claims representing services rendered January 2011 through December 2013 for 3,997,986 commercially insured individuals in the US who were 0 to 64 years of age.

STUDY DESIGN

We used multivariable logistic regression models to determine whether TB/LTBI risk factors were associated with an increased likelihood of Interferon-Gamma Release Assay (IGRA) or Tuberculin Skin Test (TST) testing in the private sector.

PRINCIPAL FINDINGS

4.31% (4.27-4.34%) received at least one TST/IGRA test between 2011 and 2013 while 1.69% (1.67-1.72%) received a TST/IGRA test in 2013. Clinical risk factors associated with a significantly increased likelihood of testing included HIV, immunosuppressive therapy, exposure to tuberculosis, a history of tuberculosis, diabetes, tobacco use, end stage renal disease, and alcohol use disorder. Other significant variables included gender, age, asthma, the state tuberculosis rate, population density, and percent of foreign-born persons in a county.

CONCLUSIONS

Private sector TST/IGRA testing is not uncommon and testing varies with clinical risk indicators. Thus, the private sector can be a powerful resource in the fight against tuberculosis. Analyses of administrative data can inform how best to leverage private sector healthcare toward tuberculosis prevention activities.

Interferon-Gamma Release Assays and Pediatric Public Health Tuberculosis Screening: The San Francisco Program Experience 2005 to 2008

BACKGROUND

Interferon-gamma release assay utilization in pediatric tuberculosis (TB) screening is limited by a paucity of longitudinal experience, particularly in low-TB burden populations.

METHODS

We conducted a retrospective review of QuantiFERON (QFT)-TB Gold results in San Francisco children from 2005 to 2008. Concordance with the tuberculin skin test (TST) was analyzed for a subset of children. Progression to active disease was determined through San Francisco and California TB registry matches.

RESULTS

Of 1092 children <15 years of age, 853 (78%) were foreign-born, and 136 (12%) were exposed to active TB cases (contacts). QuantiFERON tests were positive in 72 of 1092 (7%) children; 15 of 136 (11%) recent contacts; 53 of 807 (7%) foreign-born noncontacts; and 4 of 149 (3%) US-born noncontacts. QuantiFERON-negative/TST-positive discordance was seen more often in foreign-born/bacille Calmette-Guerin (BCG)-vaccinated children <5 years of age (52 of 56, 93%) compared to those ≥ 5 years of age (90 of 123, 73%; P = .003). Foreign-born, BCG-vaccinated children were more than twice as likely to have a discordant (79%) result as US-born, non-BCG-vaccinated children (37%; P < .0001). During 5587 person-years of follow-up of untreated children, including 146 TST-positive/QFT-negative children, no cases of active TB were identified, consistent with a negative predictive value of 100%.

CONCLUSIONS

Our experience supports the use of QFT to evaluate latent TB infection in children, particularly young BCG-vaccinated children. The proportion of QFT-positive results correlated with risk of exposure, and none of the untreated QFT-negative children developed TB. The low QFT-positive rate highlights the need for more selective testing based on current epidemiology and TB exposure risk.

Getting to Zero: Tuberculosis Elimination in California

This review of tuberculosis epidemiology is intended to provide a historical perspective on the public health approach to tuberculosis (TB) control in California. This historical context offers a lens through which to view current epidemiologic trends and insight into how new therapeutic tools can be applied. Since 1993, the year detailed case reporting was instituted, California has had a decrease in recent TB transmission as evidenced by a reduction in pediatric cases and an increased percentage of cases attributable to progression of latent infection to TB disease in the foreign-born population. Overall, there has been a dramatic decline in the annual TB case count, but the speed of the decline has slowed over the last several years. At the current pace and case count of 2137 in 2015, California will not achieve TB elimination (<1 TB case per one million population) for at least 100 years. There are an estimated 2.1 million persons in California with latent TB infection. Modeling suggests that LTBI detection and treatment are important in reaching TB elimination. For this reason, a coalition of stakeholders in California is exploring novel approaches to accelerate the case decline in order to prevent unnecessary disease and death.

Cost-effectiveness of latent tuberculosis screening before steroid therapy for idiopathic nephrotic syndrome in children

BACKGROUND

Guidelines differ on screening recommendations for latent tuberculosis infection (LTBI) prior to immunosuppressive therapy. We aimed to determine the most cost-effective LTBI screening strategy before long-term steroid therapy in a child with new-onset idiopathic nephrotic syndrome.

STUDY DESIGN

Markov state-transition model.

SETTING & POPULATION

5-year-old boy with new-onset idiopathic nephrotic syndrome.

MODEL, PERSPECTIVE, & TIMEFRAME

The Markov model took a societal perspective over a lifetime horizon.

INTERVENTION

3 strategies were compared: universal tuberculin skin testing (TST), targeted screening using a risk-factor questionnaire, and no screening. A secondary model included the newer interferon γ release assays (IGRAs), requiring only one visit and having greater specificity than TST.

OUTCOMES

Marginal cost-effectiveness ratios (2010 US dollars) with effectiveness measured as quality-adjusted life-years (QALYs).

RESULTS

At an LTBI prevalence of 1.1% (the average US childhood prevalence in our base case), a no-screening strategy dominated ($2,201; 29.3356 QALYs) targeted screening ($2,218; 29.3356 QALYs) and universal TST ($2,481; 29.3347 QALYs). At a prevalence >10.3%, targeted screening with a risk-factor questionnaire was the most cost-effective option. Higher than a prevalence of 58.5%, universal TST was preferred. In the secondary model, targeted screening with a questionnaire followed by IGRA testing was cost-effective compared with no screening in the base case when the LTBI prevalence was >4.9%.

LIMITATIONS

There is no established gold standard for the diagnosis of LTBI. Results of any modeling task are limited by the accuracy of available data.

CONCLUSIONS

Prior to starting steroid therapy, only patients in areas with a high prevalence of LTBI will benefit from universal TST. As more evidence becomes available about the use of IGRA testing in children, the assay may become a component of cost-effective screening protocols in populations with a higher burden of LTBI.

Practices and policies of providers testing school-aged children for tuberculosis, Connecticut, 2008

This study identified current practices and policies related to testing school children for latent tuberculosis infection (LTBI) in Connecticut. A cross-sectional survey was mailed to a random sample of community pediatricians and family practitioners in Connecticut who provide health care services to children aged 4-18 years. The main outcome measure was adherence to national guidelines for tuberculosis (TB) testing of school-aged children. The response rate was 66.3% (345 of 520), 258 of whom provided services to children. Responses showed that 60% (152 of 252) of replying providers read the American Academy of Pediatrics (AAP) published guidelines, and 85% routinely assess children for TB risk before skin testing although only a minority (22%) use a written questionnaire. Of 153 responding providers, 130 (85%) report that schools require formal TB risk assessments at mandated school physical examinations or at school entry. Results also showed providers who read AAP-published guidelines and who are trained in the United States are more likely to follow the national guidelines for TB testing of children. The majority of health care providers reported following AAP-published guidelines for screening school-aged children for LTBI and TB disease; however, an important number of providers still do not follow recommended guidelines. Public health officials should make efforts to increase provider awareness of, and adherence to, guidelines. School districts also should take steps to ensure the appropriate level of testing of children for TB disease and LTBI.

Latent tuberculosis infection in children: a call for revised treatment guidelines

BACKGROUND

Guidelines for latent tuberculosis infection do not consider drug-resistance patterns when recommending treatment for immigrant children.

OBJECTIVES

The purpose of this research was to decide at what rate of isoniazid resistance a different regimen other than isoniazid for 9 months should be considered.

METHODS

We constructed a decision tree by using published data. We studied 3 regimens considered to be effective for susceptible organisms: (1) isoniazid for 9 months, (2) rifampin for 6 months, and (3) isoniazid for 9 months plus rifampin for 6 months. In addition, we evaluated a regimen of isoniazid and rifampin for 3 months. Our base case was a 2-year-old child from Russia with a tuberculin skin test reaction of 12 mm. We assumed a societal perspective and expressed results as cost and cost per case of tuberculosis prevented. We conducted sensitivity analyses to test the stability of our model.

RESULTS

In our baseline analysis, rifampin was the least costly treatment regimen for any child arriving from an area with an isoniazid-resistance rate of >/=11%. Treatment with isoniazid plus rifampin was the most effective but would cost more than $1 million per reactivation case prevented. Isoniazid would become the least costly regimen if any of the following thresholds were met: rifampin resistance given isoniazid resistance of more than 82%; rifampin resistance given no isoniazid resistance of >9%; cost of rifampin more than $47/month; effectiveness of rifampin lower than 63%; effectiveness of isoniazid higher than 74%; and cost of pulmonary tuberculosis less than $7661. Isoniazid and rifampin for 3 months was the least costly for all cases from areas with isoniazid resistance of <80% as long as the regimen's effectiveness was >50% for susceptible bacteria. However, this assumption remains to be proven.

CONCLUSION

Because of the high prevalence of isoniazid resistance, rifampin should be considered for children with latent tuberculosis infection originating from countries with >11% isoniazid resistance.

Unintended consequences: mandatory tuberculin skin testing and severe isoniazid hepatotoxicity

After mandatory school-enrollment tuberculin skin testing, a 4-year-old girl who was at low risk for Mycobacterium tuberculosis infection had severe isoniazid hepatotoxicity that was managed with a liver transplant. Although severe isoniazid hepatotoxicity is very uncommon in children, this case emphasizes the need to limit skin testing to persons who have a risk factor for infection and to educate parents on how to monitor for adverse effects during treatment.