Exhibitor Catalog

School of Health and Social Care
Screening for alcohol use in
pregnancy
Lesley Smith PhD
Principal Lecturer Quantitative Research Methods
School of Health & Social Care
Oxford Brookes University
Booze & Bumps
School of Health and Social Care
Outline
• Aim of screening for alcohol misuse
• Why it is important
• Alcohol screening tools
• Availability
• Accuracy
• Screening pregnant women
• Screening tools in pregnancy
• Systematic review
• Conclusions
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Aim of screening
• Identify people at risk of alcohol related harm
• Offer advice which reduces risk of potential
harm
• Recommendation in the DOH alcohol harm
reduction strategy
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Why screening is important
• Increasing prevalence of drinking more than recommended
levels in UK
• Drinking levels and patterns in pregnant women unclear BUT
heavier prenatal drinking associated with heavier antenatal
drinking
• Whilst low to moderate consumption inconclusive effects on
the fetus – heavy and/or binge drinking harmful to the mother
• Pregnancy presents an opportunity to identify and advise
women on their drinking
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Why is screening important?
• Brief interventions shown to be effective in
reducing alcohol consumption
• though evidence in pregnant women less convincing
• Screening without an intervention has also been
shown to reduce alcohol consumption
• Identification and advice can have effects lasting
during post-partum period and subsequent
pregnancies
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Screening for alcohol use disorders
(AUDs)
• No ‘gold standard’ method for determining
alcohol consumption
• Relies on self-report
• Validity of biomarkers poor
• Standard questions about quantity and frequency
of alcohol consumption requires a trained
interviewer to elicit accurate responses (in-depth
interview)
• Impractical in the context of clinical practice
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Alcohol screening tools
•
•
Questionnaires administered by trained
personnel e.g. G.P or nurse
> 15 found for use in primary care e.g.
•
•
•
•
AUDIT, MAST, CAGE
Short versions AUDIT-C, AUDIT-3, FAST
Overall score assigned
Cut-off score defines screening positive for
an alcohol use disorder
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AUDIT-C
Q1: How often did you have a drink containing alcohol in the past
year? Never (0); Monthly or less (1); 2 to 4 times a month (2); 2 to 3
times a week (3); 4 or more times a week (4)
Q2: How many drinks did you have on a typical day when you
were drinking in the past year? 1 or 2 (0); 3 or 4 (1); 5 or 6 (2); 7
to 9 (3); 10 or more (4)
Q3: How often did you have six or more drinks on one occasion in
the past year? Never (0); less than monthly (1); monthly (2);
Weekly (3); daily or almost daily (4)
Scored on a scale of 0 - 12 (0 = no alcohol use). A score of 4 or more in
men and 3 or more in women considered positive for hazardous drinking
and need for further evaluation
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The perfect test
The size of the population is 100 and the number
of people with the problem is 30. The prevalence
of the problem is therefore 30/100 = 30%.
Loong, T.-W. BMJ 2003;327:716-719
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Results of a screening test on a hypothetical
population
Loong, T.-W. BMJ 2003;327:716-719
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Measures of accuracy
• Sensitivity is the probability of a positive test
in a person with an AUD (true positive)
• Specificity is the probability of a negative
result in a person with no AUD (true negative)
• Predictive values (PPV & NPV), Likelihood
ratios (LR), diagnostic odds ratios DOR)
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Sensitivity of a test
The test has correctly identified 24 out of the 30 people who have
the disease. Therefore the sensitivity of this test is 24/30 = 80%.
Loong, T.-W. BMJ 2003;327:716-719
School of Health and Social Care
Specificity of a test
The test has correctly identified 56 out of 70 well people. The
specificity of this test is therefore 56/70 = 80%.
Loong, T.-W. BMJ 2003;327:716-719
School of Health and Social Care
Limitations of existing tools
• Most existing alcohol-use screening tools
developed for use in men
• Developed to detect alcohol dependency
• Different thresholds for harmful drinking in
men and women
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Screening for alcohol use in pregnant
women
• Lack of consensus for a definition of harmful drinking
in pregnant women
• In UK current recommendation is to elicit response to
a single question at booking interview
• Inconsistent screening by midwives
• When is best time to screen and resources?
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Screening for AUDs in pregnant women
• Clinical guidelines for drinking levels
• Clinical guidelines for monitoring drinking levels
limited – SIGN, BMA report
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Newer screening tools
• T-ACE
• Test score 2 or more positive for risk drinking
• Risk drinking defined as 3 units or more of alcohol per
day while pregnant
• TWEAK
• 5-item instrument
• Risk drinking defined as at least 3 units a day or 14
drinks a week
• Test score 2 or more positive for risk drinking
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T-ACE
• T Tolerance: How many drinks does it take
to make you feel high? (> 2 drinks =
tolerance)
• A Have people Annoyed you by criticising
your drinking?
• C Have you ever felt you ought to Cut down
on your drinking?
• E Eye opener: Have you ever had a drink first
thing in the morning to steady your nerves or
get rid of a hangover?
Sokol et al. 1989
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Systematic review - methods
• Comprehensive searches of electronic
current to June 2008 and reference lists of
reviews and articles
• Cross-sectional studies comparing an alcohol
screening questionnaire with a structured
interview (reference test)
• Risk drinking, alcohol abuse or alcohol
dependency
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Results – study selection
Titles and abstracts retrieved from
electronic and bibliographic searches
(n = 1,374)
Articles excluded after screening title and
abstract (n = 1,342)
Potentially relevant articles retrieved for
further consideration (n = 32)
Articles meeting eligibility criteria for
systematic review (n = 6)
Excluded articles (n = 26):
Not primary study (review, guidelines, editorial or
letter (n = 10)
Not a screening accuracy study (n = 7)
Not risk drinking (1)
Ineligible reference standard for detection of
alcohol consumption (n = 4)
Brief questionnaire not used as index test (n = 1)
Population not exclusively antenatal (n = 1)
Duplicate report of an included study
(n = 1)
Unavailable from British Library (n = 1)
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Results – risk drinking
Study
Sokol 89
Russell 94
Russell 96
Chang 98
Prevalence
42/971 (4.3%)
270/4743 (5.7%)
181/2717 (6.7%)
114/350 (33%)
Tool
SENS
SPEC
PPV
CAGE
0.38
0.92
0.18
T-ACE
0.69
0.89
0.23
CAGE
0.49
0.93
0.30
T-ACE
0.70
0.85
0.22
TWEAK
0.79
0.83
0.22
T-ACE
0.88
0.79
0.23
TWEAK
0.91
0.77
0.22
T-ACE
0.92
0.38
0.39
SMAST
0.11
0.96
0.55
Dawson
2005
45/256 (17.6%)
AUDIT-C
0.95
0.85
0.57
Dawson
2001
34/404 (8.4%)
TWEAK
0.71
0.73
0.19
Positive predictive value
Positive predictive value refers to the chance that a positive test
result will be correct. That is, it looks at all the positive test results.
24 out of 38 positive test results are correct. The positive predictive
value of this test is therefore 24/38 = 63%.
Loong, T.-W. BMJ 2003;327:716-719
School of Health and Social Care
Conclusions
• T-ACE, TWEAK and AUDIT-C most promising to
detect risk drinking
• AUDIT-C also promising to detect past-year
alcohol use disorder or past-year dependence
• CAGE and SMAST of low to moderate accuracy
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What makes a good screening test?
• Accurate
• discriminate risk drinkers from low-risk drinkers
• Demonstrable benefits over existing practice
• Easy to deliver
• time, context and environment
• Acceptable to women and caregivers
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Summary
• Numerous screening tools available
• Few tested in pregnant women
• All US studies and largely low socioeconomic groups
• Unclear which tool would be most accurate
and acceptable to women and midwives in
the UK
• Methodological limitations indicate evaluation
in a UK population is warranted before
widespread use is recommended
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