Are we overestimating the beneficial effects of moderate alcohol consumption in later life? The sick quitter and sick non-starter hypotheses

Linda Ng Fat

PhD Student

UCL Population Health

Supervisors: Dr Nicola Shelton, Dr Noriko Cable, James Kneale, Professor Sir Michael Marmot

The J/U-Curve among middle age cohorts in observational studies

2Corrao, G, et al, Addiction, 2000. 95(10): p. 1505-1523.

Alcohol consumption against risk of coronary heart disease

J-Curve for Total mortality; ex-drinkers separated

Klatsky, A. L. and N. Udaltsova (2007). Annals of Epidemiology 17(5): S63-S67

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Is the relationship causal?

• Meets Bradford Hill Criteria of Consistency of findings and biological plausibility

- Alcohol may increase high-density lipoprotein (HDL) cholesterol

• Some evidence to suggest this is the case from RCT & change in biomarkers. But limited due to – Small sample size & duration– No RCT for incidence of CVD

Thus majority of studies have relied on observational data

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Examples of reporting in the media

Source: BBC News 5

A health message that is confusing?

• 26% of people drink alcohol because they believe it to have health benefits (Mintel 2004).

• In US a third cited possible health benefits as a

motivation, whilst only 10% identified breast cancer as a risk (Mukamal et al 2008)

Implications of the J-shape

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Further criticisms outside the sick-quitter bias

1. Moderate drinkers have a better social position and adopt healthier lifestyles than non-drinkers.

2. Validity of the ‘lifetime abstainer group’

3. Poor health may be a reason why some people never ever start drinking

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Odds of being a non-drinker vs. drinker aged 18 to 34 years Health survey for England 2006 & 08

Odd

s R

atio

(an

d 95

% C

.I)

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Adjusted for age, ethnicity, region, income, education, marital status, parental status, LLSI, anxiety, physical activity and smoking

NG FAT, L., & SHELTON, N. Addiction, 2012. 107(9): p. 1612-1620.

Odds of being a non-drinker vs. drinker aged 18 to 34 yearsHealth survey for England 2006 & 08

Highest QualificationIncome

Odd

s R

atio

(an

d 95

% C

.I)

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Adjusted for age, ethnicity, region, income, education, marital status, parental status, LLSI, anxiety, physical activity and smoking

NG FAT, L., & SHELTON, N. Addiction, 2012. 107(9): p. 1612-1620.

The Sick Non-starter hypothesis

• Non-drinkers have higher rates of self-reported poor health in young adulthood (Power, C 1998) even after adjusting for a range of social and demographic factors (Ng Fat, L & Shelton, N 2012)

• Poor health a reason why some never ever take up drinking?

HypothesesA. Poor health precedes non-drinking early in the life course

B. Continuous poor health is associated with continuous non-drinking

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Data sets

The National Child Development Study 1958 (NCDS)

The British Cohort Study 1970 (BCS)

A

AB

B

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Data sets

The National Child Development Study 1958 (NCDS)

The British Cohort Study 1970 (BCS)

A

AB

B

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NCDS 1958

Medical conditions at 16 years (p<0.05)

Drinking frequency at 23 years

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BCS 1970Self-report conditions suffered since 16 years

reported at 26 years (p<0.05)

Drinking frequency at 26 years14

Logistic Regression

Outcome:

1.Lifetime abstainer: Non-drinker in each sweep (NCDS 1958 and BCS 1970)

2.Self-identified lifetime abstainers: Current status measure from those who reported “never having had an alcoholic drink” (BCS 1970)

Exposure:

Change in limiting longstanding illness since 23 (NCDS 1958)

Change in longstanding illness since 26 (BCS 1970)

Controls: Sex, malaise inventory score (mental health), highest qualification, marital status, parental status

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Odds ratios

Adjusted for sex, highest qualification, marital status, parental status and malaise score

Lifetime abstainers

33 yearsNo

LLSI LLSI23 yearsNo LLSILLSI

Life time abstainers

Self-identified LA

30 years 30 yearsNo LLI LLI

NO LLI LLI

26 yearsNo LLI 1 0.80 1 1.29LLI 1.14 2.80*** 2.07* 2.11*

NCDS 1958 BCS 1970

1 1.442.82** 4.50**

NG FAT, L., et al (2013) Journal of Epidemiology and Community Health, doi:10.1136/jech-2013-202576

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Odds ratios

Adjusted for sex, highest qualification, marital status, parental status and malaise score

Lifetime abstainers

42 yearsNo

LLSI LLSI23 & 33 yearsNo LLSI 1 2.13**LLSI 3.16*** 7.02***

Life time abstainers Self-Identified LA

34 years 34 years

No LLI LLINO LLI LLI

26 &30 yearsNo LLI 1 1.02 1 1.13

LLI 1.71 3.33*** 2.02** 2.80***

NCDS 1958 BCS 1970

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NG FAT, L., et al (2013) Journal of Epidemiology and Community Health, doi:10.1136/jech-2013-202576

Conclusions and Implications

• Poor health from an early age and persistent poor health is associated with persistent non-drinking (lifetime abstention) from early adulthood

• Non-drinkers in later life may suffer from double bias from sick-quitters and sick non-starters, therefore may be an inadequate reference group against drinkers

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Strengths

Limitations•Small sample size of lifetime abstainers•Missing lost to attrition (MNAR)•Participants may drink in between waves

• Consistent findings from two large representative cohorts and between two measures of non-drinkers (lifetime abstainer and self-identified LA)

• Consistent findings between two measures of health (LLI and LLSI)

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Acknowledgements: Dr Nicola Shelton, Dr Noriko Cable, Dr James Kneale, Professor Sir Michael Marmot

l.ngfat.10@ucl.ac.uk, @linsng

NG FAT, L., CABLE, N., MARMOT, M. & SHELTON, N. (2013) Persistent long-standing illness and non-drinking over time, implications for the use of lifetime abstainers as a control

group, Journal of Epidemiology and Community Health, doi:10.1136/jech-2013-202576

NG FAT, L., & SHELTON, N Associations between self-reported illness and non-drinking in young adults. Addiction, 2012. 107(9): p. 1612-1620.

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Impact