Iodine Supplementation an overview Kate Jolly Professor of

Iodine Supplementation: an overview Kate Jolly Professor of Public Health & Primary Care University of Birmingham

Methods of iodine supplementation • Salt fortification with iodine – Universal: fortification of all salt for human and animal consumption (USI) – Fortification of all salt for human consumption – Fortification of salt used in certain foodstuffs e. g. bread

Methods of iodine supplementation • Fortification of animal fodder (Finland) • Accidental by product of iodophores used in dairy industry • Iodised oil • Iodised water, sugar, tea… • Oral supplements for pregnant or lactating mothers - (where <90% of households are using iodised salt and median UI is <100µg/l in school children)

Current UK guidance for pregnancy supplements • Recommended supplements: – 400 µg folic acid from before pregnant until 12 weeks pregnant – 10 µg vitamin D daily throughout pregnancy • Do not take vitamin A • Healthy Start vitamins available from 10 weeks gestation – contain folic acid; vitamins C and D • Iodine guidance – SACN recommend no increase in iodine intake during pregnancy: 140 µg/day – WHO recommend 250 µg intake daily

What supplements do UK women take during pregnancy? • Infant Feeding Survey 2010 – 94% women took folic acid before or during pregnancy – 79% took folic acid during first trimester – 64% took other vit/min during pregnancy • Bestwick et al (Plos One 2014; 9(2): e 89354) – 150, 000 women attending A/N screening 2011 -12 – 30. 7 took folic acid pre-pregnancy – 61% took folic acid during pregnancy – Only 7. 6% did not take folic acid supplements

Survey in Birmingham 2014 • Hospital serving multi-ethnic population • Women approached at dating scan before 14 weeks gestation • 198 women approached, • 180 (90%) response

The sample • Age – 12 (6. 7%) <20 years – 157 (87. 2%) 20 -40 years – 11 (6. 1%) >40 years • Post school education 80 (44. 4%) • First pregnancy 69 (38. 3%) • Ethnic group – 72 (40. 0%) white – 60 (33. 3%) South Asian • English not first language 56 (31. 1%) • Born in UK 118 (65. 6%)

Survey Results • 38. 9% took pre-pregnancy supplements • 98. 3% took a supplement during the first trimester • 41. 7% definitely took iodine containing supplement • 51. 7% probably took iodine containing supplement

Iodine supplementation Iodine No iodine P value Age: Teenagers 20+ years 4 (33. 3) 89 (53. 0) 8 (66. 7) 79 (47. 0) 0. 19 Ethnicity: White Other 42 (58. 3) 51 (47. 2) 30 (41. 7) 57 (52. 8) 0. 14 First language: English Other 72 (58. 1) 21 (37. 5) 52 (41. 9) 35 (62. 5) 0. 01 Education: School Further education 43 (44. 3) 49 (61. 3) 54 (55. 7) 31 (38. 8) 0. 03 Parity: Primips Multips 57 (51. 4) 36 (52. 2) 54 (48. 6) 33 (47. 8) 0. 91

Costs & benefits of iodine supplementation for pregnant women in mildly iodine deficient population Monahan M, Boelaert K, Jolly K, Chan S, Barton P, Roberts T Lancet Diabetes and Endocrinology 2015; 3(9): 712 -722

Aims and Approach • To compare the costs and benefits of a strategy of iodine supplementation for pregnant women in a mild to moderately iodine deficient population against no iodine supplementation • A model based analysis • Assumptions aimed to limit the benefits of iodine supplementation and over-estimate potential harms

Methods 1: Decision tree The model is identical at every node ending with [+]

Assumptions relating to iodine • IQ gain taken from Bath et al – 2. 2 points in mild/mod deficiency – 3. 0 points in children of severely deficient mothers • Prevalence of deficiency 68% (Vanderpump) • 11% of those with deficiency were severely deficient (Bath) • Women took iodine supplements from early pregnancy until cessation of exclusive breastfeeding

Assumptions relating to pregnancy losses and complications • Estimates from literature of pregnancy loss, stillbirth, preterm birth and pre-eclampsia • Increased risk of thyroid dysfunction from iodine supplementation 0. 25% (EC 2002) • IQ loss from hypothyroidism and hyperthyroxinaemia: 7 points (Haddow) • Estimates of increased pregnancy loss, stillbirth, preterm birth and pre-eclampsia from thyroid dysfunction

Findings • NHS perspective: a saving of £ 199 per/women supplemented & 1. 22 IQ points gained • Societal perspective: a saving of £ 4476/women & 1. 22 IQ points gained • Iodine supplementation dominated the sensitivity analyses: – IQ gain for severe deficiency same as mild/mod – 1 IQ point gain for mild/mod deficiency – Halved prevalence of iodine deficiency – Doubled cost of iodine tablets….

Limitations • IQ gains could lead to shift in population norms, so relative differences remain • Uncertainty over the precise estimation of the impact of IQ on earnings. NHS perspective did not use this earnings based IQ value but still shows cost saving • Iodine status at individual level would strengthen argument and avoid unnecessary supplementation • Lack of evidence of potential harms

Conclusions • Currently only about half of women take iodine supplements in pregnancy • Lower in more socio-economically disadvantaged • Policy for all pregnant women to take iodine supplements cost effectiveassuming IQ gains seen in Bath et al (2011) and prevalence of deficiency from Vanderpump et al (2011)