Summary of studies reporting prevalence of developmental language disorder
| Author (year) | Study design | Sampling strategy | Country, city | Setting | Age group | Screening tool | Methods of data collection | Sample size | Prevalence (%) |
| Eapen et al (2004)17 | Cross-sectional | Random stratified sampling | UAE, Al Ain, Dubai, Ras Alkhaima | National households | 3 years | Denver Developmental Screening Test (DDST) + language screening procedure for 3-year-olds by Westerlund and Sundelin | Face to face | 694 | 9.9% |
| Gad-Allah et al (2012)23 | Cross-sectional | Multistages stratified random sampling | Eygpt, Mansoura, Belkase, Met Salsil, Aga | Nursery schools | 3–6 years | Structured questionnaire designed by the authors | Face to face | 852 | 19.7% |
| Al-Fadhli et al (2017)22 | Cross-sectional | Unclear | Saudi Arabia, Eastern Province | Community (unclear where the community sample was drawn from) | 3–5 years | Arabic Ages and Stages Questionnaire (A-ASQ) | Not clear | 1235 | 24.45% |
| Gharib et al (2017)30 | Cross- sectional | Convenience sample | Egypt, Alexandria | Hospital, children, outpatient clinic | 3–6 years | National Health Service-Lothian Guidelines for Referral to Speech and Language Therapy | Face to face | 280 | 3.2% |
| Saeed et al (2018)40 | Cross-sectional | Convenience sample | Iraq, Baghdad | Hospital, psychiatry clinic | <7 years | Developmental Milestones by the Centres for Disease Control and Prevention (CDC) | Face to face | 353 | 11.9% |
| Youssef et al (2020)33 | Cross-sectional | Convenience sample | Egypt, Assiut, Helwan | Two hospitals | mean age 5 years | Arabic language test | Not clear | 212 | 16.04% |
| Shatla et al (2020)36 | Cross-sectional | Convenience sample | Saudi Arabia, Makkah | 10 primary care centres | 36 months, 48 months and 60 months | A-ASQ | Face to face | 948 | 5.6% |
| Alakeely et al (2022)37 | Cross- sectional | Convenience sample | Saudi Arabia, Riyadh | Well-baby clinics | 1–5 years | CDC-validated Arabic language milestone screening test | Face to face | 250 | 25.6% |
| Metwally et al (2023)34 | Cross- sectional | Multistage cluster random sampling technique | Egypt, Cairo, Fayoum, Assuit, Aswan, Damietta, Dakahlia, Gharbia and Marsa Matrouh | Households | 12–71 months | The revised Denver Prescreening Developmental Questionnaire Arabic adapted version and DDST, second edition | Face to face | 21 316 | 4.2% |