Introduction  

Globally, a common practice in childhood development is to screen children to determine if there are any key developmental problems that need to be assessed.1 These screens typically check for problems relating to general health, including hearing, vision, height, weight and oral health. They also often screen for emotional, behavioural or intellectual issues that might be evident.2 Hall and Stewart-Brown3 categorise four types of screening programmes: (1) biochemical; (2) screening involving objective measures (such as height and weight, vision and hearing); (3) screening involving physical examination; and (4) screening involving understanding of child development.

In New Zealand (NZ), the screen is called the B4 School Check (B4SC), and it is administered to children aged 4 years. It is the final and most comprehensive in a series of eight free Well Child Tamariki Ora visits that children receive,4 and currently the only one for which comprehensive linked data are available to examine coverage. The B4SC was implemented in NZ starting in September 2008, although it was not universal until 2010. There are eight key developmental areas that are assessed: vision, hearing, oral health, general health, growth measurement, strengths and difficulties (Strengths and Difficulties Questionnaire [SDQ]) as reported by parents and teachers and a parental evaluation of development status (PEDS). If concerns are identified in any area, children are referred for further testing or intervention. The B4SC is administered by the Ministry of Health, which has set a target 90% participation rate across the country, with parents and guardians being notified of the B4SC via enrolment with a primary health organisation (PHO; organisations that provide primary care services5). The Ministry’s data suggest they have been meeting their target since 2013, but compliance falls short of 100%.6 Furthermore, not all children are registered with a PHO (95% of children aged 0–4 years are registered7), and including unregistered children in the denominator will further reduce compliance rates.

This raises three concerns: first, that a non-trivial number of children are missing their checks. Second, that some children may not be registered with a PHO and, as such, their parents are not notified that their child should attend a B4SC. Third, that these children may be more likely to be in higher risk categories for later health problems and could benefit from the referrals to interventions that accompany this screen. It is this final concern that is the focus of this study.

Evidence preschool/school entry screening participation

Across different universal health checks available to the adult populations of different countries certain patterns persist: those in poorer socioeconomic circumstances, with lower qualifications and at greater risk of health problems are less likely to attend such checks.8–13

The available evidence for universal health checks in childhood suggests a similar pattern.14–16 Wood et al 15 considered the coverage of universal child health reviews in Scotland. They considered two cohorts of children, the first, born in 1998/1999 were eligible for five health checks (10 days/6–8 weeks/8–9 months/22–24 months and 39–42 months) and a second cohort, born in 2007/2008, were only eligible for the first two checks. They found that coverage rates of the 10-day check were very high in both cohorts (99%), but this declined as the children aged. For the review of 6–8 weeks, coverage was between 94% and 95%, and for the review of 39–42 months, the coverage rates fell to 86%. There were clear deprivation gradients, with children living in the least deprived areas much more likely to have a health check than those in the most deprived areas, and these gradients increased substantially with increasing age and decreasing coverage. They conducted an audit on a subset of the areas included in the review (Glasgow and Fife). Consistent with the inverse care law,17 they found that children who missed the review of 6–8 weeks were more likely to require additional health services and support in the future than those who attended the review.

Similarly, evidence from Denmark suggests that participation declines with age. Only 76% of eligible children attend the age 4 health screen. Child, parent and household level characteristics predicted attendance with children who had been hospitalised at least twice since birth, children of single, younger, less educated or immigrant parents and children residing in low-income households or living in institutions less likely to participate.16 Similarly, in North Carolina, children of mothers who were younger, less educated, black and unmarried were also less likely to receive an adequate number of well child visits.14

The overall aim of these universal checks is to identify children who are at risk of later problems and direct them towards interventions that will reduce this risk. The early identification of health and developmental issues increases the efficacy and cost-effectiveness of treatment and lessens the risk of any potential comorbidities. However, evidence about whether childhood screening achieves this aim is mixed.18–20 Childhood screening relies on accurate identification of children at risk and also on the availability of effective interventions or treatments for at-risk children, which are not always available.19 21 Regardless, universal checks are often the only instrument to identify children in need of additional services, who may otherwise be missed by the health system. Therefore, systematic differences in attendance highlight a crucial issue: those children most in need are missing out on vital services.

In NZ, we are in a unique position to examine the characteristics of those not completing the B4SC. Many routinely collected government databases (including B4SC) are held in the Statistics New Zealand Integrated Data Infrastructure (IDI) and each individual is assigned a unique identifier that allows their records to be linked across data files. In this analysis, we build a population cohort using birth records and immigration/emigration files to determine which children aged 4 years were in the country and eligible for the B4SC between 1 July 2011 to 30 June 2015, and then we examine the characteristics of those who do not get the B4SC.

The aim of this paper is to identify characteristics associated with non-participation in the B4SC by linking to deprivation, birth, census, health, disability and immunisation records, all of which are available in the IDI.

Methods

Outcomes

Results

Table 1 shows the total number of children in the denominator (eligible) population for each year, and the number and percentage of children who completed the VHT, nurse and SDQT components of the B4SC by year. In all years, completion was highest for the VHT component and lowest for the SDQT component. Approximately 52%–62% of children completed the SDQT component, compared with 78%–87% for the nurse components and 86%–91% for the VHT components. Coverage was lowest in 2011/2012 and highest in 2014/2015.

Tables 2 and 3 show the associations between completion of each B4SC component for 2011/2012 to 2014/2015 (all years combined) and a range of characteristics. Sociodemographic characteristics are reported in table 1 and health and perinatal characteristics in table 2. The tables show the number and percentage of children completing each B4SC component, the OR and 95% CIs.

Most of the sociodemographic characteristics presented in table 1 were significantly associated with B4SC completion. Children were more likely to complete a check if they: were of European (compared with not European) or Asian (compared with not Asian) ethnicity; had fewer siblings; came from areas of lower socioeconomic deprivation; had a mother with a bachelor’s degree; had mothers aged 30–34 years; lived in a home that was owned rather than rented; lived in a smaller (2–4 person) household; and lived in a household that does not receive benefit income.

The health and perinatal characteristics presented in table 2 were all significantly associated with B4SC completion. Children were more likely to complete a B4SC if they: had a mother that had never smoked; weighed between 2500 g and 4000 g at birth; had a gestational age of between 37 weeks and 42 weeks; were not referred for disability support; spent more time enrolled with a GP; and had lower numbers of hospital and emergency department admissions and spent fewer days in hospital.

Discussion

Our results demonstrate that Māori and Pacific children, those in poorer socioeconomic circumstances and with poorer health are less likely to complete the B4SC. Children living in areas of higher socioeconomic deprivation, without a father named on the birth certificate, with mothers and fathers with lower levels of education, living in households with five or more people, having multiple changes in residence in the early years of life and living in rental accommodation have a lower likelihood of B4SC completion. Children with indicators of poor health outcomes including having a mother who smokes and having a low birth weight also have a lower likelihood of B4SC completion. Given that these factors tend to be associated with poorer child health outcomes,36 37 our results paint a consistent pattern, demonstrating that across a wide range of measures of vulnerability, those children who would potentially most benefit from a B4SC screen, and the referrals to interventions are less likely to participate.

A strength of this study is the large, linked dataset that was used (the IDI). The IDI is a whole population data source, and therefore, it allows us to include children who are often excluded from other analyses, such as those not in regular contact with health services. Furthermore, the large number of data sources included in the IDI allows us to examine a wider range of characteristics than would be available in any single source.

While this study is novel and provides vital information for service providers, all of the analyses presented in this paper are bivariate. It is likely that children who are disadvantaged in one area are also at a disadvantage in other areas (ie, the predictors of B4SC completion are correlated). Multivariate analysis would provide more detailed information about the joint or relative impact of different predictors on B4SC completion. However, to run multivariate analysis, we would have to restrict our sample to children born in NZ, with a mother and father who completed 2013 census. These restrictions would reduce the sample to less than 70% of the total sample and would exclude all migrants, making the results difficult to generalise to the whole population. For this reason, we have chosen not to undertake multivariate analysis in this paper.

Our findings are consistent with existing literature on the coverage of child health checks14–16 and provide further support for the inverse care law—that those with the greatest need are the least likely to seek services.17 There is currently very little research in this area for child health screens, but the application of the inverse care law is a consistent finding among free health checks for the adult population.8–13 However, the reasons why people most in need do not attend are not well understood, and there is a need for qualitative research investigating why parents are not taking children to free health checks.

Several potential explanations for non-attendance at adult health checks have been put forward that may be applicable to child health checks including lack of awareness, time constraints and access issues,10 and misunderstanding the purpose/scepticism. Focus groups conducted with low income Māori and Pacific parents have identified concerns about relevance of the B4SC checks, children and parents being judged and language and cultural understanding as potential barriers to participation.38 Lack of awareness of the checks was also identified as a problem, and this may be a particular issue for children who are not enrolled on the PHO system (5% of children) or who have incorrect address information and thus do not receive the invitation letter. Access could also be an issue with many of the B4SC being carried out by Plunket or other health services that are only open during normal office hours and not at weekends.38 39 Therefore, households where both parents work or single-parent working households will not easily be able to attend. Furthermore, for less densely populated regions in NZ, there are fewer centres offering B4SC, compared with more densely populated regions such as Auckland, Wellington or Christchurch,39 meaning it is less convenient to attend. Scepticism about the value of attending and the purpose of the screens is likely to differ by ethnic group, as research persistently demonstrates that Māori receive a poorer quality and slower service and are less likely to receive appropriate levels of care.40–42 There are similar findings for Pacific peoples also.43–45 Therefore, these groups may be less trusting of the NZ health system.46

Socioeconomic and ethnic inequalities in health-seeking and health outcomes within NZ are well documented for both the adult and child population.44 45 47 A long-standing objective of the NZ government is to reduce health and socioeconomic disparities, particularly for Māori and Pacific families. Patterns of participation at the B4SC could be reinforcing existing ethnic and socioeconomic disparities. Early intervention is one means of reducing inequities.48 49 Although evidence for the effectiveness of childhood screening is mixed, at present, it appears that any potential benefits that do result from the B4SC will be unevenly distributed across ethnic and socioeconomic groups. Improving B4SC participation would be a cost-effective path towards converging outcomes and would ensure that any benefits from the screen are reaching children who are most at risk of later health concerns.

Although 100% attendance in the B4SC is unlikely, we believe that a greater effort is required to reach the most vulnerable families to ensure that more children who would benefit from the B4SC will get access to the interventions that arise from it. This will require greater outreach and public awareness, but also examining whether access and cultural relevance of the B4SC could be improved. Interventions such as phone, letter or text message reminders have been shown to increase the uptake of health checks and are one option that could be explored to increase B4SC uptake.50 51

An area where there has been some success in getting increased services to hard-to-reach populations has been through mobile programmes and services.52 53 For example, in America, community health vans have shown success in reaching underserved populations such a low-income minority groups and immigrants for a range of health needs including earlier access to prenatal care and disease prevention screening.54–56 The Family Van run by Harvard Medical School offers a diverse range of health services and has saved an estimated $2.8 million in avoided emergency room visits over the last 5 years with an estimated $23 saving per $1 spent.57 In addition, direct contact with those not participating should be considered with a greater push to ensure that those with characteristics of vulnerability are encouraged to attend. Further research is necessary on barriers to attendance identified and remedial action taken.

We have not followed children to determine whether missing a B4SC does in fact have an impact on later life outcomes, and this clearly needs to be assessed. We plan to address this question in future work, although the limited time series for the B4SC means that we will only be able to examine outcomes up to age 12 years.

Conclusion

Using a rich and diverse range of measures, we find that children with indicators of socioeconomic deprivation or poor health are less likely to participate in the B4SC and as such they may miss referrals for programmes and interventions that may increase their readiness to enter school. We believe the patterns we observe in B4SC participation suggest a potential reinforcing of existing inequalities and require increased effort to ensure that all children are tested and screened and that those with the greatest need get access to health services, programmes and interventions.