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Table 4 Risk factors considered by included studies for prioritization of risk-based targeted screening in paediatric populations

From: 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

Year Study Setting Study Population Risk Factors Considered for Risk-based Screening Definition or Measurement of Risk Factors Implications for Risk-based Screening in the Canadian Indigenous Population
Population/Community-Level Risk, Incidence-Based Risk
 Alvarez [24] 2014 Nunavut, Canada A high-risk Indigenous community in Iqaluit, Nunavut Community-level high TB incidence Communities with > 5 TB cases in the past 5 years considered high-incidence Community-level incidence rates may be an effective guide for prioritizing screening in Canadian Indigenous communities.
 Minodier [30] 2010 Montreal, Canada Immigrant children and their classmates in Montreal, Canada Immigrant status, or being in the same class as a child with immigrant status NA The study’s conclusion that case identification would have been improved by targeting only immigrant children, rather than screening entire classes that contain immigrant children suggests that increased consideration should be given to the actual incidence rates underlying the classification of certain groups as high-risk, rather than basing screening solely on membership of or contact with these groups themselves.
 Yuan [28] 1995 Toronto, Canada High-risk (indigenous or immigrant) school children Birth in a TB-endemic country
Being Indigenous
NA Similar to Minodier et al.’s findings above (2010), the fact that this strategy was found to be cost-ineffective suggests the importance of incidence-based screening in specific communities, rather than screening entire demographic groups based on status, i.e. Indigenous/immigrant.
 Panchal [33] 2014 Leicester, UK Recent immigrants to Leicester, UK Immigrant status Immigrants identified upon first registering for primary care Number needed to screen (NNS) was lowest in certain strata of the immigrant population, according to age and TB incidence in their country of origin (specifically 16–35 year olds from areas with TB incidence ranging from 150 to 499/100000), highlighting again the relevance of incidence-based screening in the case of potentially high-risk sub-populations in low-burden countries.
 Pareek [35] 2011a UK Immigrants attending 177 Primary care facilities in the UK Sub-factors for risk among immigrants:
- Age
- TB incidence in country of origin
- Geographic region of origin
TB incidence > 40/100,000 in country of origin among < 16 year-olds
TB incidence > 500/100,000 in country of origin, regardless of age
Immigrating from Sub-Saharan Africa
See above
 Pareek [34] 2011b Lancashire, Yorkshire and London, UK Immigrants attending healthcare centres in the UK Sub-factors for risk among immigrants:
- Age
- TB incidence in country of origin
TB incidence > 40/100,000 in country of origin among < 16 year-olds
TB incidence > 250/100,000 in country of origin among 16–35 year-olds
See above
Individual Risk
 Trehan [36] 2008 USA Internationally adopted children in the US International adoption NA The rationale for screening in this population is again related to the high TB incidence rates in certain countries of origin, highlighting the utility of actual incidence-based screening.
Malnourishment Weight-for-age z score <−2.0 Although malnourishment was not a factor considered for initial targeted screening in this study, the finding that malnourished children are more likely to have a positive TST upon repeat testing indicates the potential relevance of including this risk factor in targeted screening efforts among Canadian Indigenous children, as Indigenous communities in Canada are characterised by a high prevalence of food insecurity. (It should be noted that the possibility of boosting of TST reactivity upon repeat testing is acknowledged in the study, but that it is considered less likely to have had an effect in the study, as repeat testing was conducted 3 months after initial testing).
 Flaherman [31] 2007 California, USA Pre-kindergarten children in California High-risk children based on risk factor questionnaire The presence of one or more risk factors included in the Paediatric Tuberculosis Collaborative Group Risk Factor Questionnaire [63] a As the study found risk-based screening more cost-effective, the use of a risk factor questionnaire to guide targeted screening may be warranted in the Canadian Indigenous population, if adapted based on risk factors relevant to the Indigenous context, such as poor housing conditions, food insecurity and relevant co-morbidities (See b).
 Bergamini 2009 Various (see Table 2) Regular contact with an active TB case (e.g. having a household member with TB) NA Although these studies evaluated the accuracy of screening tools rather than a risk-based screening strategy, close contact with an active TB case is a relevant risk factor to consider for targeted screening in paediatric Indigenous communities, due to the comparatively high prevalence of TB in this population in comparison to the overall Canadian population.
 Connell 2006
 Grare 2010
 Grinsdale 2016
 Sali 2015
 Salinas 2011
 Salinas 2015
 Alvarez [5] (Canadian TB Standards) b 2014 Canada Canadian Indigenous people Renal disease
HIV co-infection
Inadequate housing
NA The Indigenous population experiences a higher prevalence of these risk factors for TB infection than the general Canadian population, underlining their potential relevance in risk-based screening in Indigenous communities.
  1. aThis risk factor questionnaire was initially developed for use in the U. S. and includes the following factors:
  2. 1) Birth of the child outside the U. S.
  3. 2) Travel outside the U. S.
  4. 3) Exposure to an active TB case
  5. 4) Close contact with an individual who has had a positive TST
  6. 5) Contact with anyone who has been in jail or a shelter, uses illegal drugs, or is HIV-positive
  7. 6) Consumption of unpasteurized dairy products
  8. 7) Birth of a household member outside the U. S.
  9. 8) Travel of a household member outside the U. S.
  10. Administering a TST was recommended in the original study in the case of the presence of > 1 of the above factors. [63]