chp6 results upgraded version by data sub-group

CHP6 Results *UPGRADED VERSION*

By Data Sub-group

Pilot Study

Total doors knocked184

Uncontactable88

Doors answered96

Uneligible1

Participated30

Rejected49

Uncontactable16

Fully completed28

Partially completed2

Fieldwork

Total doors knocked2046

Uncontactable487

Doors answered1559

Uneligible119

Participated687

Rejected668

Uncontactable85

Fully completed682

Partially completed5

Demographics of study sample

Is our sample representative of the population?

Age & Gender

Ethnic group & Marital status

Educational level & Personal yearly income

Housing type

Prevalence of the usage of dietary supplements in Singaporean adults

(“use” and “dietary supplements” as defined by Lit Review)

Prevalence

No. of different supplements used

n: 382 Median: 2 Inter-quartile

range: 1 – 4

Average length of use n: 380 Median:

3 yrs Inter-

quartile range:1 yr 3 mnths – 6 yrs 3 mnths

Longest length of use n: 380 Median:

4 yrs 6 mnths

Inter-quartile range: 2 yrs – 10 yrs

Spending on supplements per year n: 348 Median:

$200 Inter-

quartile range:$100 – $600

Prevalence & proportion prescribed by group of supplement

Supplement group

Usage Prevalence

Proportion of total uses (n)

Proportion prescribed by

Western doctor

Animal products 36.5 % 37.2 % (437) 7.6 %

Vitamins / Minerals

35.4 % 35.9 % (422) 30.3 %

Herbal products 27.4 % 27.0 % (317) 1.9 %

Overall 55.6 % 100.0 % (1176)

14.2 %

Prevalence for top 10 supplements

Factors associated with the use of dietary supplements

What Lit Review tells us Factors established to have positive association

with the use of dietary supplements Female gender High education level High socio-economic status Alcohol drinking High physical activity Non-obese / low BMI Concern with healthy diet, vegetarians Stressful lifestyle Presence of a medical condition, medication use Positive view of the potential health benefits of using

supplements

What Lit Review tells us Factors with contradictory reports on

association with the use of dietary supplements Age Smoking Self-perceived health status

Statistical tests used To evaluate relationship between 2 qualitative

variables Chi-square test

Pearson chi-square & Fisher’s exact test for p values Linear-by-linear association for trend

To evaluate relationship between a quantitative and a qualitative variable Independent samples t-test & One-way analysis of

variance (ANOVA) For t-test, equal variances assumed or unassumed is used

depending on p value from Levene’s test Log transformation using ln (is done first if continuous

variable is not normally distributed) Results presented after re-conversion back to geometric

mean & relative mean difference

Gender

Male(306)

Female (381)

0%

10%

20%

30%

40%

50%

60%

70%

47.1%

62.5%

Pre

vale

nce

of

sup

ple

men

t u

se

Use of supplement

Gender PR 95% CI p

Male (306) 1.000 (reference) -

Female (381) 1.327 (1.152 - 1.530) 0.000

Education level

No formal(108)

Primary(162)

Secondary(189)

Tertiary(192)

0%

10%

20%

30%

40%

50%

60%

70%

38.9%

54.3%63.0%

58.0%

Pre

vale

nce

of

supple

ment

use

Use of supplement

Education level PR 95% CI p

Overall p = 0.001

No formal qualification (108) 1.000 (reference) -

Primary (PSLE) (162) 1.397 (1.061 - 1.840)

0.013

Secondary (O level / N level / ITE) (189) 1.619 (1.248 - 2.101)

0.000

Tertiary (A level / Polytechnic / University) (192)

1.492 (1.149 - 1.938)

0.001

Ethnic group Ethnic group is not a significant factor

affecting the use of dietary supplements in general

It becomes significant only when we stratify by specific supplement useUse of Manuka etc honey / Royal jelly

Ethnic group Prevalence

PR 95% CI p

Chinese (529) 9.5% 1.000 (reference) -

Malay (49) 24.5% 2.159 (1.25-3.729) 0.013Use of Multi-vitamins


PR 95% CI p

Chinese (529) 6.2% 1.000 (reference) -

Indian (94) 13.8% 2.217 (1.213-4.052) 0.017

Ethnic group

Use of Calcium


PR 95% CI p

Chinese (529) 17.8% 1.694 (1.015 - 2.829)

0.040

Malay & Indian (143) 10.5% 1.000 (reference) -

Use of Cordyceps


PR 95% CI p

Chinese (529) 5.5% 7.839 (1.077 - 57.057)

0.011


Use of Bird's Nest


PR 95% CI p

Chinese (529) 7.4% 3.514 (1.102 - 11.206)

0.019


Ethnic group

Use of Berry extracts


PR 95% CI p

Chinese (529) 10.6% 3.784 (1.396 - 10.261)

0.003


Use of Echinacea


PR 95% CI p

Chinese (529) 6.4% 9.191 (1.269 - 66.566)

0.006


Household income per year

Below $24,000

(219)

$24,000 to $72,000

(224)

$72,001 and above(78)

0%

10%

20%

30%

40%

50%

60%

70%

80%

49.3%58.5%

66.7%

Pre

va

len

ce o

f su

pp

lem

en

t u

se

Use of supplement

Household income per year PR 95% CI p

Overall p = 0.017; p for trend = 0.053

Below $24,000 (219) 1.000 (reference) -

$24,000 to $72,000 (224) 1.186 (0.997 - 1.411)

0.057

$72,001 and above (78) 1.352 (1.100 - 1.662)

0.008

Household income per yearSpending on supplements in 1 year (S$) (among

users)

Household income per year

Geometric mean

Relative mean

difference

95% CI p

Overall p = 0.010

Below $24,000 (219) 178.70 1.000 (reference) -

$24,000 to $48,000 (144)

283.67 1.587 (1.092 – 2.308) 0.016

$48,001 and above (158)

292.89 1.639 (1.147 – 2.342) 0.007

Smoking status

0%10%20%30%40%50%60%70% 57.9%

44.3%

Pre

vale

nce o

f supp

lem

ent

use

Use of supplement

Smoking status PR 95% CI p

Non / Ex smokers (570) 1.000 (reference) -

Current daily / occasional smokers (115)

0.766 (0.617 – 0.951)

0.010

Confounding We suspect gender to be a confounder for

smoking statusSmoking status

Gender

Use of supplement

Confounding

Male Stratum Use of supplement




0.913 (0.702 – 1.188)

0.539

Female Stratum Use of supplement




0.703 (0.417 – 1.185)

0.135

Crude (unstratified) Use of supplement




0.766 (0.617 – 0.951)

0.010

Confounding After stratification by gender, using the

Mantel-Haenszel ratio calculation, the adjusted PRR for smoking is 0.860, which is 12.3% different from the crude ratio of 0.766.

Since this difference is >10%, it could be significant.

Thus, gender is a potential confounder for smoking with regards to its effects on the use of supplements.

It could be investigated further by using multi-variate analysis.

Physical activity

Yes(380)

No(304)

46%

48%

50%

52%

54%

56%

58%

60% 59.2%

51.0%

Exercise at least once a week

Pre

va

len

ce o

f su

pp

lem

en

t u

se

Use of supplement

Exercise at least once a week PR 95% CI p

Yes (380) 1.161 (1.011 - 1.333)

0.037

No (304) 1.000 (reference) -

View that diet provides sufficient nutrients

Yes(441)

No / Don't know(242)

48%

50%

52%

54%

56%

58%

60%

62%

52.6%

61.2%

Pre

vale

nce

of

sup

ple

men

t u

se

Use of supplement

Diet provides sufficient nutrients

PR 95% CI p

Yes (441) 1.000 (reference) -

No / Don’t know (242) 1.163 (1.017 - 1.330)

0.036

Diagnosed with chronic disease(s)

Presence (310) Absence (374)48%

50%

52%

54%

56%

58%

60%

62%

59.7%

52.4%

Pre

va

len

ce o

f su

pp

lem

en

t u

se

Use of supplement


PR 95% CI p

Yes (310) 1.139 (0.997 - 1.301)

0.057

No (374) 1.000 (reference) -


Use of animal product


Prevalence

PR 95% CI p

Yes (310) 41.3% 1.255 (1.032 - 1.528)

0.023

No (374) 32.9% 1.000 (reference) -


Average length of use across all supplement(s) used (months) (among users)

Chronic disease

Geometric mean

Relative mean

difference

95% CI p

Yes (310) 38.31 1.339 (1.034 – 1.733) 0.027

No (374) 28.61 1.000 (reference) -Longest length of use across all supplement(s)

used (months) (among users)

Chronic disease

Geometric mean

Relative mean

difference

95% CI p

Yes (310) 52.57 1.154 (1.026 – 1.804) 0.032

No (374) 38.63 1.000 (reference) -

Specific chronic diseases diagnosed

Yes(42)

No(642)

0%

10%

20%

30%

40%

50%

60%

70%

80% 71.4%

54.7%

Diagnosed with Arthritis

Pre

va

len

ce o

f su

pp

lem

en

t u

se

Use of supplement


PR 95% CI p

Yes (42) 1.306 (1.066 – 1.603)

0.037

No (642) 1.000 (reference) -

Yes(12)

No(672)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100% 91.7%

55.1%

Diagnosed with Osteoporosis

Pre

va

len

ce o

f su

pp

lem

en

t u

se

Specific chronic diseases diagnosed

Use of supplement

Diagnosed with Osteoporosis

PR 95% CI p

Yes (12) 1.665 (1.385 – 2.000)

0.015

No (672) 1.000 (reference) -

View that supplements are effective in improving health

0%

20%

40%

60%

80%

14.3%28.3%32.0%

65.6%81.8%

Pre

vale

nce o

f su

pple

ment

use

Use of supplement

View that supplements are effective

PR 95% CI p


Strongly disagree / Disagree (60) 0.833 (0.516 - 1.344)

0.510

Neutral (153) 1.000 (reference) -

Strongly agree / Agree (471) 2.095 (1.649 - 2.661)

0.000

View that there is scientific evidence for the use of supplements

Stro

ngly d

isagr

ee

(8) Disa

gree

(94) Neu

tral

(195

)Agr

ee

(341

)

Stro

ngly a

gree

(46)

0%

20%

40%

60%

80%

100%

37.5%36.2%47.7%

61.9%87.0%

Pre

vale

nce

of

supple

ment

use

Use of supplement

View that there is scientific evidence

PR 95% CI p

Overall p = 0.000


0.065



0.000

View that supplements can have harmful side effects

0%

20%

40%

60%

80%

100%100.0%

63.0%44.4%

56.8%75.0%

Pre

vale

nce o

f su

pple

ment

use

Use of supplement

View that can have side effects PR 95% CI p

Overall p = 0.000


0.000



0.004

Overview of characteristics & relation to use of supplement Significantly related & shown in this ppt

Gender Ethnic group Education level Household income Smoking status Physical activity View that diet is sufficient Presence of chronic disease Diagnosed with Arthritis & Osteoporosis View that supplements are effective View that supplements have scientific evidence View that supplements can have harmful side effects

Green – shown by Lit Review to be positively relatedYellow – inconclusive evidence from Lit Review

Overview of characteristics & relation to use of supplement Not significantly related, but still shown in this

ppt Age Body mass index Healthy diet (fruits / vegetables) **to be confirmed

again


Overview of characteristics & relation to use of supplement Not significantly related & not shown in this ppt at

all Marital status Occupational status Alcohol intake Pack-years of smoking Months since quit smoking Dietary restriction Diagnosed with other specific chronic disease Pregnancy Self-perceived health status Stress in lifestyle Adequacy of sleep


Profile of a typical supplement user Female Has up to secondary or tertiary level education Has high household income per year Is a non-smoker Exercises at least once a week Views that diet does not provide sufficient

nutrients Is diagnosed with chronic disease(s), particularly

Arthritis and Osteoporosis Views that supplements are effective in improving

health and that there is scientific evidence for their use

Not significant - Age

Use of supplement

Age Prevalence

Overall p = 0.235

21-39 (young adults) (227)

55.9%

40-59 (middle-aged) (302)

58.3%

60 and above (elderly) (158)

50.0%

Age

Use of supplement

Geometric mean

p

User (381) 44.35 0.775

Non-user (303) 44.68 -

Not significant - Body mass index (BMI)

Use of supplement

Body mass index Prevalence

Overall p = 0.525

<23 (normal / underweight) (332) 54.8%

23 and above (overweight / obese) (330)

57.3%

Body mass index

Use of supplement

Mean p

User (371) 23.61 0.977

Non-user (291) 23.62 -

Healthy diet **not confirmed**

Use of supplement

Servings of fruit or vegetables consumed per day

Prevalence

Overall p = 0.731

0 (17) 52.9%

0.5 and 1.0 (70) 51.4%

1.5 and above (598) 56.2%

Servings of fruit or vegetables consumed per day

Use of supplement

Mean p

User (381) 2.88 0.960

Non-user (304) 2.88 -

A look at Calcium in detail

The top of the list supplement

Gender

Male(306)

Female (381)

0%

5%

10%

15%

20%

25%

8.5%

22.6%

Pre

vale

nce

of

Calc

ium

use

Use of Calcium

Gender PR 95% CI p


Female (381) 2.657 (1.759 - 4.011) 0.000

Gender stratified by age (>55)

Male(84)

Female (74)

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

16.7%

47.3%

Pre

vale

nce

of

Calc

ium

use

Age > 55 Stratum Use of Calcium

Gender PR 95% CI p


Female (74) 2.248 (1.288 - 3.921) 0.003

Age

21-39(227)

40-59(302)

60 and above(158)

0%

5%

10%

15%

20%

25%

11.0%

17.2%

22.2%

Pre

vale

nce

of

Calc

ium

use

Use of Calcium

Age PR 95% CI p

Overall p = 0.012

21-39 (young adults) (227) 1.000 (reference) -

40-59 (middle-aged) (302) 1.563 (1.002 - 2.439)

0.047

60 and above (elderly) (158) 2.011 (1.225 - 3.223)

0.004

Reasons, sources of information & KAP

What is the most common reason for using dietary

supplements?

What Lit Review tells us The motivations for taking supplements can

be varied and include ensuring nutritional adequacy, reducing one’s risk for certain diseases and age-related changes, and enhancing physical performance.

Women are more likely to be using supplements to promote weight loss, burn-up fat, prevent colds, improve memory, and relieve stress; whereas men are more likely to use supplements to enhance athletic performance, retard the onset of aging, build muscle, and improve sexual function.

Reason(s) for taking supplement(s)

n = 846

Reason(s) stratified by age group

n = 846

p = 0.000

p = 0.389

p = 0.000

p = 0.255

p = 0.011

p = 0.018

p = 0.137

p = 0.136

p = 0.086

Stratified by gender – cosmetic purpose

Male(144)

Female(238)

0%

2%

4%

6%

8%

10%

12%

14%

16%

18%

3.5%

16.0%

Use

of

sup

ple

men

t fo

r co

smeti

c p

urp

ose

(am

on

g

use

rs)

Use of supplement for cosmetic purpose

Gender PRR 95% CI p


Female (238) 4.547 (1.832 - 11.287) 0.000

Is there an association between particular supplements and

special reasons for taking them?(Reasons stratified by

supplement)

For cosmetic purpose

p = 0.002

p = 0.000

p = 0.013

p = 0.117

To compensate for deficiencies in diet

p = 0.049

p = 0.075

p = 0.049

p = 0.000

What is the most common way people are introduced to dietary

supplements?

What Lit Review tells us The relative ease with which individuals can

access information on an extensive number of topics (eg. via the Internet) has increased interest in the use of dietary supplements.

Source(s) of information among users

n = 648

Source(s) of information stratified by age group

n = 648

p = 0.002

p = 0.011

p = 0.019

p = 0.210

p = 0.671

p = 0.289

Stratified by supplement – Traditional Medicine practitioner

p = 0.011

p = 0.007

p = 0.002

p = 0.003

p = 0.290

Questionable sources of information? Among all users who strongly agree or agree

that supplements can have harmful side effects (163), 46.6% (76) obtain information about supplements

from friends & family and/or advertisements only (and no other sources)

Among all users who strongly agree or agree that supplements have scientific evidence for use (251), 45.8% (115) obtain information about

supplements from friends & family and/or advertisements only (and no other sources)

What is the most common reason for not using dietary

supplements?

Reason for not taking supplement

n = 302

How does knowledge of dietary supplements influence their

perceived effectiveness?

What Lit Review tells us Women and those with higher education are

more likely to use supplements based on evidence-based indications.

View that there is scientific evidence for the use of supplements

View supplements are effective

View that there is scientific evidence

PR 95% CI p



0.144



0 .000

0%

20%

40%

60%

80%

100%

25.0%41.5%49.2%

85.6%91.3%

Pro

port

ion w

ho v

iew

that

supple

ments

are

eff

ect

ive

Chronic diseases & supplement use

Top 5 chronic diseases

Our study MOH 2007

Chronic disease

Prevalence (n)

% on regular

medication(s)

% using supplement(

s)

Prevalence

Hyperlipidemia 21.5 % (148) 66.2 % 58.1 % 12.5 %

Hypertension 20.7 % (142) 83.1 % 59.9 % 12.0 %

Diabetes mellitus

8.0 % (55) 96.4 % 49.1 % 4.6 %

Arthritis 6.1 % (42) 57.1 % 71.4 % 10.1 %

Asthma 5.2 % (36) 58.3 % 61.1 % 6.6 %

Specific chronic diseases & supplements

Use of Combined vitamins & minerals

Diagnosed with Hyperlipidemia

Prevalence

PR 95% CI p

Yes (148) 3.4% 0.342 (0.139 - 0.839)

0.012

No (536) 9.9% 1.000 (reference) -

Use of Manuka etc honey / Royal jelly

Diagnosed with Diabetes mellitus

Prevalence

PR 95% CI p

Yes (55) 0.0% - - 0.002

No (629) 12.9% 1.000 (reference) -


Yes(42)

No(642)

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

38.1%

15.0%


Pre

va

len

ce o

f C

alc

ium

use

Use of Calcium Use of Glucosamine / Chondroitin


PR 95% CI p PR 95% CI p

Yes (42) 2.548 (1.662 - 3.906)

0.000

3.335 (1.942 - 5.728)

0.000

No (642) 1.000 (reference) - 1.000 (reference) -

Yes(42)

No(642)

0%

5%

10%

15%

20%

25%

30%

35%

28.6%

8.6%


Pre

va

len

ce o

f G

luco

sam

ine

/

Ch

on

dro

itin

use


Yes(36)

No(648)

0%

2%

4%

6%

8%

10%

12%

14%

16%

18% 16.7%

5.6%

Diagnosed with Asthma

Pre

va

len

ce o

f B

ird

’s N

est

use

Use of Bird’s Nest

Diagnosed with Asthma

PR 95% CI p

Yes (36) 3.000 (1.353 - 6.653)

0.018

No (648) 1.000 (reference) -

Drug-supplement interactions Among those with at least 1 chronic disease

diagnosed (310), 26.1% (81) are on medication(s) only 18.1% (56) are on supplement(s) only 41.6% (129) are on both medication(s) and

supplement(s) 14.2% (44) are on neither

448156 129

n = 310

supplement medicationpresence of chronic disease

Drug-supplement interactions 32.5% of all supplement users are on regular

medication(s) for chronic disease(s) 88.6% of all those on regular medication(s) for

chronic disease(s) use at least 1 supplement Among supplement users on medication(s) for

chronic disease(s), 23.0% know about the possible drug-supplement

interaction(s) 49.6% have discussed the usage of supplement(s)

with their doctor 23.4% have discussed the usage of supplement(s)

with their doctor AND none of the supplements used were prescribed by a doctor

Example Aspirin-Gingko increases risk of bleeding (as

cited in the article by Dima M. Qato et al.) From our study,

9.5% of those on regular medications for Heart disease (likely to be on Aspirin) are also using Gingko extracts 10.0% of those using Gingko extracts are on regular

medications for Heart disease Among all Gingko users on medication(s) for

chronic disease(s), 16.7% are aware of the possible drug-supplement

interactions 50.0% have discussed the usage of supplement with

their doctor

Summary of important findings 55.6% of the Singaporean adult population use

dietary supplements. Calcium is the most widely used dietary

supplement. 14.2% of all supplement uses are prescribed by a

Western doctor. Half of the population spend between $100 – $600

on dietary supplements per year. The most common reasons for taking dietary

supplements are to improve general health and to prevent disease.

Reasons for use change depending on age, gender and supplement used.

Summary of important findings People mostly get their information about dietary

supplements from family & friends and advertisements.

The most important reasons keeping people from using dietary supplements are that they are unnecessary and too expensive.

Knowledge of the scientific evidence of dietary supplements increases their perceived effectiveness.

There exists drug-supplement interactions which people are largely not aware of.

About half of those on regular medication(s) and also using supplements have not discussed the issue of supplement usage with their doctors.

Summary of important findings The use of dietary supplements is associated with

female gender, high education level, high socioeconomic status, non-smoker, physical activity, presence of a chronic medical condition (especially Arthritis or Osteoporosis), positive opinion of supplements and the view that one’s diet is insufficient.

Chinese are more likely to use Bird’s Nest, Cordyceps, Echinacea and Berry extracts.

Knowledge of the harmful side effects of dietary supplements do not seem to matter.

Use of dietary supplements is unrelated to age, alcohol drinking, obesity, self-perceived health status or stress levels.

Thank you

Questions? Suggestions?

Prepared answers to possible questions

“Prepared answers” Q. In the questionnaire, people taking

Combined vitamins & minerals or Multi-minerals could have also responded yes to taking Calcium, causing the prevalence to be falsely high?

A. Out of 112 who responded yes to taking (single) Calcium, only 18 (16.1%) also responded yes to taking Combined vitamins & minerals and/or Multi-minerals. The remaining 94 (83.9%) form the majority who

responded yes to taking (single) Calcium only

“Prepared answers” Q. Since response rate is only 50.7%, what

about refusal bias? A. Out of 668 units which rejected us, we

managed to capture simple demographic data (gender, ethnicity & age) for 127 units (19.0%)

See next 2 slides for comparison graphs.

Gender & Ethnic group

p = 0.165 p = 0.061

Estimated age

p = 0.002

“Prepared answers” Q. Can you give other examples of significant drug-

supplement interactions besides Aspirin-Gingko? A. (Summary of Lit Review team’s research) In clinical

practice, polypharmacy is common, and to the mixture physicians prescribe, patients add various over-the-counter medications, vitamins, herbs, and foods.

For example, Warfarin is known to interact with Garlic, Gingko, Glucosamine, Omega fatty acids / Fish oil & Vitamin E. The consequence is prolonged INR and increased risk of bleeding. Intracerebral haemorrhage, subdural haematoma and spontaneous hyphema are possible.

As a precaution, patients on Warfarin should have INR measured within a week of starting any supplement.

Patients may not be forthcoming about the use of supplements, even if it causes severe adverse effects, because they fear censure.

Fruits (not the kind of results we expect!)

Use of supplement

Servings of fruit consumed per day

Prevalence

PR 95% CI p

0 (120) 47.5% 1.000 (reference) -

0.5 & above (565) 57.3% 1.207 (0.987 - 1.476)

0.055

Use of vitamin/mineral

Servings of fruit consumed per day

Prevalence

PR 95% CI p

0 (120) 25.0% 1.000 (reference) -

0.5 & above (565) 37.5% 1.501 (1.082 - 2.083)

0.009

Vegetables

Use of supplement

Servings of vegetables consumed per day

Prevalence

PR 95% CI p

0 – 1.0 (270) 60.0% 1.000 (reference) -

1.5 & above (415) 52.8% 0.880 (0.770 - 1.005)

0.070

Use of animal product


Prevalence

PR 95% CI p

0 – 1.0 (270) 42.2% 1.000 (reference) -

1.5 & above (415) 33.0% 0.782 (0.643 - 0.951)

0.015

Vegetables

Use of Combined vitamins & minerals


Prevalence

PR 95% CI p

0 – 1.0 (270) 10.0% 1.000 (reference) -

1.5 & above (415) 7.5% 0.567 (0.346 - 0.927)

0.025

chp6 results *upgraded version* by data sub-group

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chp6 results upgraded version by data sub-group