South African Food sensitisation and Food Allergy study (SAFFA) - - PowerPoint PPT Presentation

South African Food sensitisation and Food Allergy study (SAFFA) Cape Town 2013/2014

Principal Investigators Dr Claudia Gray Prof Mike Levin Researchers Dr M Botha Wisdom Basera Heidi Facey-Thomas

1

Introduction

• The prevalence of allergic disorders such as asthma,

allergic rhinitis and eczema has been rising rapidly in rapidly urbanising communities in several African countries

• Food allergy traditionally perceived to be rare in Africa
• There is emerging evidence however that this might be

changing and that we might be seeing the start of the “second wave” of allergic diseases especially in rapidly developing countries on the continent – mirroring what has happened in high income countries over the last few decades.

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FA Prevalence in Preschool children (< 5yrs)

Prescott et al.World Allergy Organisation Journal 2013,6:21

Objectives

To determine the prevalence of IgE-mediated Food sensitisation and Food Allergy in unselected 12-36 month old children in Cape Town.

Adverse reaction to food Non toxic

(food hypersensitivity)

Toxic

(microbiological Pharmacological)

Non immune mediated (Food intolerance) Immune mediated (food allergy)

Other

Pharmacological

Enzymatic

Non IgE mediated

IgE mediated

Methodology

Sampling Tools

• Questionnaire
• Skin Prick Test

Peanut, egg, cow’s milk, soya, wheat, fish, hazelnut

• Open Oral Food Challenge

SPT≥1mm; NOT proven tolerant to age appropriate portion

Non-participants

sex, age, ethnicity, history of atopy

Recruitment and Assessment

470 eligible children 310

66% response rate

291

94participation rate

284

98% completed 7 incomplete 19 nonparticipants 160 Non-responders

SAFFA Demographics: Ethnicity

SAFFA study participants

N=284

Black African 46% Mixed Race/Coloured 42.4% Caucasian11.6%

Cape Town census 2011:

Children 0-4 years

Black African 46.4% Mixed Race/Coloured 45.4% Caucasian 8.2%

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Results

284

Participants 245 SPT -ve

39

SPT≥1mm

26

Tolerant

13

Not tolerant

8

OFC -ve 5 OFC +ve

9

• 86.3%

Not Allergic

• 12% Sensitised

but not allergic

• 1.8%

Food Allergic

Spectrum of sensitisation and Food Allergy

Overall

n 95% CI

Egg Peanut Cow’s Milk Hazelnut Soya Wheat Fish SPT≥1mm 11.6%

33 9.7-17.8

9.5% 5.3% 3.5% 1.8% 1.8% 1.4% 1.1% SPT≥3mm 9.9%

28 6.4-13.3

7.8% 3.2% 1.8% 0.7% 0.7% SPT≥7mm 4.2%

12 1.9-6.6

3.9% 1.1% 0.4% 0.4 OFC positive 1.8%

5 0.6-4.1

1.4

4 0.4-3.6

1.1

3 0.2-3.1

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SAFFA: Prevalence of Polysensitisation Total number of foods sensitised to

1 2 ≥3 86.3% 245 8.5% 24 2.8% 8 2.5% 7

SAFFA study: Unpublished data August 2014

Sensitisation and ethnicity

SPT Any Food Black African n=131 Mixed race n=118 Caucasian n=33 P-values

≥1mm 9.9% 13.6% 12.1% 0.7% ≥3mm 9.2% 10.2% 12.1% 0.8% ≥7mm 2.3% 5.9% 6.0% 0.3%

Summary (1)

• Food allergy point prevalence in unselected

urban South African children in a representative sample of 12-36 month old children = 1.8%

• Provides a basis for further monitoring of a

population possibly only at the beginning of the food allergy epidemic.

• High sensitisation rates in Black African and

Mixed race children are similar to the high rates

• f aeroallergen sensitisation seen in unselected

and allergic populations.

Summary (2)

• Further objectives for the SAFFA study

– Describe prevalence of socio-demographic, environmental and family related risk factors in study population – Compare prevalence of sensitisation and food allergy between

• urban Caucasian, Mixed race and black African children with

more power in larger sample size.

• rural and urban Black African Xhosa children

– Generate population-specific cut-off levels for SPT and Immunocaps with 95%positive predictive values.

Thank you