Table 4 Risk factors considered by included studies for prioritization of risk-based targeted screening in paediatric populations
Author (Reference) | 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 Diabetes HIV co-infection Malnourishment 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. |