Key messages
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Children with low language proficiency (LLP) (difficulties) may meet problems with speaking, understanding language, and literacy (ability to read) as they grow older. They also have psychological and social difficulties later in life, but the evidence is less certain for these outcomes than for learning outcomes.
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It is unclear whether early language skills affect later independence and participation in everyday life, as the evidence is very limited and uncertain.
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We need more long-term, high-quality studies with large samples and comparison groups to understand which children are most affected and how early language difficulties affect later outcomes, particularly independence and participation in daily life, where current evidence is limited.
Low language proficiency in children
Children with LLP have difficulties with speaking, understanding, or using language in early childhood. These difficulties can affect how children learn to read, communicate with others, and take part in everyday activities at school and at home. For some children, early language difficulties improve over time. For others, they continue as children grow older and may affect later learning, social relationships, and independence.
What did we want to find out?
We wanted to see whether children with low language skills at ages four to eight years old continue to have problems with language, reading, and quality of life as they grow up.
What did we do?
We searched for studies of children between the ages of four and eight years who were identified as having LLP. These children either scored below average on language tests or had a clinical diagnosis. We analysed outcomes related to language and reading, as well as five areas of quality of life:
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psychological well-being (mental health)
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physical health
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independence
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social relationships (making friends)
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participation in everyday life such as work and community life
We combined the results of the studies using statistical methods (meta-analysis) and took into account that some outcomes were related to each other.
What did we find?
We found 80 studies (that took place in North America or Europe) which followed children with LLP into adolescence or adulthood and reported outcomes from 15 different groups of children (cohorts), with about 28,800 children in total.
Children with LLP are likely to continue:
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having difficulties with language and reading into adolescence and adulthood.
These difficulties were noticeable and consistent across studies. Children with LLP may also be at higher risk of:
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mental health problems, such as depression or anxiety
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difficulties with making friends
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less independence in daily life
We do not have enough evidence to know whether they have problems with physical health.
What are the limitations of the evidence?
Some studies in this review had limitations that affect how confident we can be in the results.
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We are highly confident that children with LLP have difficulties with literacy (ability to read) when growing up.
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We are moderately confident that children with LLP have difficulties with language when growing up, because some of the children in the studies dropped out. However, our results were generally consistent.
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We are moderately confident that children with LLP experience more mental health problems (e.g. problems with making friends) and a lack of participation in everyday life when growing up. Our confidence is only moderate because of small studies (for participation) or variation between studies. Generally, patterns were consistent but further evidence may change our results.
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We have low confidence that children with LLP have difficulties with becoming independent when growing up, because of very few studies. Further evidence is likely to change our results.
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We are not confident that children with LLP have difficulties with physical health when growing up. The evidence is very uncertain.
The way low language proficiency was described and measured sometimes varied between studies. Some outcomes — especially physical health, independence, and participation in daily life — were only reported in a few studies. Some studies were small or included only certain groups of children. Important factors, such as non-verbal IQ or other health conditions, were not always reported. The results also varied between studies, which means that not all children with LLP are affected in the same way. Overall patterns are consistent, but some findings should be interpreted carefully.
How up to date is this evidence?
The evidence is up-to-date to March 2025.
อ่านบทคัดย่อฉบับเต็ม
Low language proficiency (LLP) affects up to 10% of children, depending on how it is defined, and is a known risk factor for academic and social difficulties. Despite growing awareness, there is limited consensus on the long-term consequences of LLP across quality of life domains. This review synthesises evidence from longitudinal cohort studies to evaluate long-term risks associated with LLP identified between ages four and eight, with follow-up from age 12 onwards.
วัตถุประสงค์
To examine the long-term outcomes of children aged four to eight years with low language proficiency (LLP), in terms of language, literacy, and quality of life across five WHO domains (physical, psychological, independence, social relationships, and environment).
วิธีการสืบค้น
CENTRAL, MEDLINE, Embase, PsycINFO, ERIC, and 17 other databases were searched without language or date restrictions. In addition, reference lists were checked, citation searching was conducted, and study authors were contacted to identify additional studies. The most recent search was completed in March 2025.
เกณฑ์การคัดเลือก
We included prospective or retrospective longitudinal cohort studies that identified children with LLP between ages four and eight years and assessed outcomes at age 12 or older. Studies could include comparison groups or single-cohort designs. LLP was defined either using standardised diagnostic criteria (≤ –1 SD on normed language measures, encompassing ~10–15% of the population) or clinical judgement by qualified professionals.
การรวบรวมและวิเคราะห์ข้อมูล
We extracted data on language, literacy, and World Health Organization (WHO) quality of life domains and used robust variance estimation (RVE) meta-analysis models, including hierarchical and correlated effects models. Effect sizes were reported as Hedges' g or risk ratios (RR), with Grading of Recommendations, Assessment, Development and Evaluation (GRADE) applied to each outcome domain. We conducted sensitivity and moderator analyses and assessed small-study effects.
ผลการวิจัย
We included 80 studies; 72 contributed to meta-analyses across 15 independent cohorts (≈ 28,828 participants). Studies were published between 1982 and 2024 and conducted in Europe and North America. Risk of bias, assessed across study participation, attrition, and outcome measurement, varied; only three studies were at low risk across all assessed domains, with study attrition most frequently rated as moderate or high.
Language outcomes showed large adverse associations in long-term follow-up (145 effect sizes; 11 cohorts; Hedges’ g = –1.36, 95% Confidence Interval (CI) –1.80 to –0.92; moderate certainty). Literacy outcomes were similarly affected (86 effect sizes; 7 cohorts; g = –1.12, 95% CI –1.28 to –0.96; high certainty). Physical outcomes were reported in only one study and could not be meta-analysed; evidence was insufficient to draw conclusions.
Psychological outcomes showed moderate adverse associations (91 effect sizes; 7 cohorts; g = –0.50, 95% CI –0.80 to –0.19; moderate certainty), with risk ratio analyses indicating lower probability of favourable psychological outcomes (RR = 0.53, 95% CI 0.42 to 0.67). Independence outcomes showed smaller and more uncertain associations (17 effect sizes; 2 cohorts; g = –0.59, 95% CI –1.35 to 0.18; low certainty). Social relationship outcomes showed moderate adverse associations (35 effect sizes; 6 cohorts; g = –0.64, 95% CI –1.35 to 0.07; moderate certainty). Environmental outcomes showed large but imprecise adverse associations (23 effect sizes; 5 cohorts; g = –1.10, 95% CI –1.47 to –0.73; moderate certainty).
Across domains, sensitivity analyses supported the robustness of findings, although degrees of freedom were often low due to the limited number of independent cohorts. Where binary outcome data were available, risk ratio estimates were directionally consistent with continuous outcomes but frequently imprecise.
ข้อสรุปของผู้วิจัย
Early low language proficiency (LLP) is consistently associated with substantial long-term language and literacy difficulties. LLP is also associated with poorer psychological well-being and social relationship outcomes later in life, with moderate certainty of evidence. Associations with independence outcomes are smaller and more uncertain, reflecting limited data and low certainty. Environmental outcomes, including education, employment, and societal participation, show large adverse associations, although estimates are imprecise due to the small number of contributing cohorts. Physical health outcomes remain under-researched. Taken together, these findings indicate that childhood LLP is not a transient delay but a marker of enduring developmental vulnerability, underscoring the need for sustained identification and support across developmental stages. Further high-quality longitudinal studies are needed, particularly in under-represented outcome domains.
แหล่งทุน
Internal sources
Department of Special Needs Education, University of Oslo, Norway, supported the preparation of the protocol and review to be carried out during office hours for ÅMH, KR, and MM-L.
Department of Education, University of Oslo, Norway, supported the preparation of the protocol and review to be carried out during office hours for AL.
External sources
The Research Council of Norway, Norway
This review is part of the project, Better Equipped, which is funded by the Research Council of Norway, Grant 324207. Lervåg and Melby-Lervågs participation was founded by The Research Council of Norway, Centres of Excellence, Grant 331640. The funder had no role in the study design, conduct, methods, data analysis, reporting, or publication of this protocol for the review.
การลงทะเบียน
https://discovery.ucl.ac.uk/id/eprint/10165057/1/Hagen_et_al-2023-Cochrane_Database_of_Systematic_Reviews.pdf
