??????????? -?Vitamin C??????-

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???????????-?Vitamin C??????-

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• ??980814
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• ??????
• ????????????
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• ????
• ?Vitamin C??????

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??????

• ????????????,?????????????????????????????,???????
  ??????????????,???????????

e?
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????????????
Professor Archibald Leman Cochrane, CBE FRCP
FFCM, (1909 - 1988) ???????

• 1972??????????Archie Cochrane?????????????????????
  ????,????????(RCT)???,??????????????????????????,?
  ???????????

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????????????

• 1980????????Sackett D.????Mc Master???????????????
  ?????,?????????????
• 1992?Evidence-based medicine?????Mc
  Master??Gordon Guyatt??,??JAMA??????????????????,?
  ???????????
• ????????????
• ???Modified PBL???
• ????????????
• ???????????

Dr. David L. Sackett
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????????????

• 1992????????????????,??Archie Cochrane????,????199
  3?Cochrane Collaboration??? ?????????,??Cochrane
  Library,??????????????

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????????
Clinical Expertise ????
EBM
Best Research Evidence ????
Patient Values ?????
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???????????

• Therapy/Prevention??/?????
• ?????????????
• ?????????????????
• Diagnosis????
• ????????????????????
• ??McBurneys sign ??????????????????
• Harm/Etiology??/????
• ?????????????
• ????????????????????????
• Prognosis??
• ???????????
• ????Ransons criteria ?????????????

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???????????

• 1. ??????????????????
• 2. ??????????
• 3. ???????????????
• 4. ?????????????
• 5. ??????????????

Accessing ???
Appraising ????
Applying ????
Auditing ????
Asking ???
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Step1?????????????????

• ?????????
• ??????????????????(background question)?????(foreg
  round question)

?????? ????? ????
?????? ?????? ????
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Foreground questions

• Ask for specific knowledge about managing
  patients with a disorder
• PICO
• Patient and/or problem
• Intervention (exposure, test)
• Comparison intervention (if relevant)
• Outcomes
• ??????????????????,??????????E?beta-carotene,????
  ????????????,??????

P High CV risk male I Vitamin E and
beta-carotene C No Vit E and beta-carotene O
Clinical events or death
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Step 2?????????

• ?????? Databases
• ?????????????
• MD Consult, Uptodate
• ???????????????
• Medline. PubMed
• ?????????
• Cochrane Library, ACP journal club
• ??????? Searching strategies
• ????????
• ????/?
• ????????
• ???????????
• ?????????????,?????????,??????????
• ?????? Hierarchy of evidence

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????
Level Level Therapy/Prevention, Aetiology/Harm
1 a ???????????(RCT)???????(systematic review SR)???
1 b ????????????RCT??
1 c ??????????,???????????,??????????????
2 a ?????????(cohort studies)??????????
2 b ????????????RCT??(????80follow-up)
2 c ??????????????????
3 a ???????????(case control studies),??????????
3 b ?????????(individual case control study)
4 ??????,?????????????
5 ?????????????????,???????
???Oxford Centre??????
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Step 3??????????????

• ??????????? (Validity)
• ???????????? (Importance)
• ????????????,???????,??????,????????

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??????1

• ????(Original Study)
• 1. ??????(Randomized Control Trial)
• ?????????????,??????
• ??????aspirin,??????,?????????????
• 2. ????(Cohort Study)
• ??????/???????,????????
• ?????????aspirin ????aspirin ??,???????????
• 3. ??????(Case Control Study)
• ?????????,?????/??????
• ????500 ????????500 ????????,???aspirin????
• 4. ????(Case Report)
• ???????????,???????????
• ????5 ??aspirin ????????????????,???????????????

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??????2

• ????(Review of Literature)
• 1. ?????(systemic review)
• ????????,???????????????????????,?????????,???????
  ???,???????????,?????????(Meta-Analysis
  ????),???????????
• 2. ??????(non-systemic review)
• ??????,?????????????????????,?????????????,???????
  ????

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Step 4????????????

• ??????????????
• ?????
• ????
• ??/????
• ??????????????
• ???????????????
• ?????????
• ??????????????
• ?????????????

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Step 5??????????????

• ???????????
• ??????????????
• ??????????
• ?????????????
• ?????????
• ???????????
• ??????????????????
• ?????????
• ?????????????
• ?????????????????
• ????????????
• ????????????????????
• ???????????????

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?????????--?Vitamin C??????
Asking ???

• ????
• ??????????????????,????Vitamin C????????????
• ??????(PICO)
• ????
• ???????

Patient adult
Intervention Vitamin C
Comparison Non-Vitamin C
Outcomes Common cold incidence, Duration
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Step2?????????
Accessing ???

• ???Cochrance library, PubMed, ???
• ???Common cold, vitamin C, incidence

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Cochrane Library
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Cochrane Library
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PubMed
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CEPS???
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Step 3??????????????
Appraising ????

• Background??
• The role of vitamin C (ascorbic acid) in the
  prevention and treatment of the common cold has
  been a subject of controversy for 60 years, but
  is widely sold and used as both a preventive and
  therapeutic agent.

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• Objectives??
• To discover whether oral doses of 0.2 g or more
  daily of vitamin C reduces the incidence,
  duration or severity of the common cold when used
  either as continuous prophylaxis or after the
  onset of symptoms.

Vitamin C
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• Search strategy????
• Cochrane Central Register of Controlled Trials
  (CENTRAL)
• MEDLINE (1966 to December 2006)
• EMBASE (1990 to December 2006)
• Selection criteria????
• Excluded??
• dose less than 0.2 g per day of vitamin C
• no placebo comparison.
• Included??
• (1) 0.2 g/day or more, and less than 1 g/day
• (2) 1 g/day or more, and less than 2 g/day
• (3) 2 g/day or more.

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• Outcome measures????
• 1.Incidence???
• colds during prophylaxis was assessed as the
  proportion of participants experiencing one or
  more colds during the study period
• 2.Duration????
• mean days of illness of cold episodes
• 3.Severity???
• episodes was assessed in two ways
• days confined indoors
• off work or off school per episode
• symptom severity scores

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• Analysis????
• 1.Prophylaxis??
• incidence of colds
• duration of colds
• severity of colds
• 2.Therapeutic??
• duration of colds
• severity of cold episodes
• 3.Adverse effects???
• high dose vitamin C intake

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1.1 Prophylaxis incidence of colds
??? (Risk Ration RR) ???? (Relative Risk RR)
???????/????? ?????????????????12/4170.029(2
.9), ???????????2/3250.0062(?0.62)? ??????(RR
)2.9/0.624.7 ?????????????????????????4.7??
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1.2 Prophylaxis duration of colds
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1.3 Prophylaxis severity of colds
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2.1 Therapeutic duration of colds
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2.2 Therapeutic severity of colds
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Summary of main results

• Effect on common cold incidence prophylaxis
  trials
• The pooled RR was 0.96 (95CI 0.92 to 1.00)
• A subgroup of six trials involving a total of 642
  marathon runners, skiers, and soldiers on
  sub-arctic exercises reported a pooled RR of 0.50
  (95 CI 0.38 to 0.66)
• Effect in common cold duration prophylaxis
  trials
• A consistent benefit was observed, representing a
  reduction in cold duration of 8 (95 CI 3 to
  13) for adults and 13.6 (95CI 5 to 22) for
  children
• Effect in common cold duration and severity
  therapeutic trials
• No significant differences from placebo were
  seen.
• Safe of vitamin C
• No serious symptoms

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Authors conclusions

• The failure of vitamin C supplementation to
  reduce the incidence of colds in the normal
  population indicates that routine mega-dose
  prophylaxis is not rationally justified for
  community use.
• But evidence suggests that it could be justified
  in people exposed to brief periods of severe
  physical exercise or cold environments.

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Step 4????????????
Applying ????

• Q ????vitamin C????????
• Q ?????????vitamin C?????????????

• A ?????????????????vitamin C??????????,??,???????
  ??????????,??vitamin C?????????????

• A ?????????vitamin C???????????

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Step 5????
Auditing ????
??1 ??????? ??1 ??????? ??1 ???????
1 ???????????
2 ?????????????
3 ??????????????
??2 ????????? ??2 ????????? ??2 ?????????
1 ??????????????????????
2 ???????????????????????
3 ??????????????
??3 ??????? ??3 ??????? ??3 ???????
1 ????,??????????????????
2 ???????????????????????
??4 ?????????????? ??4 ?????????????? ??4 ??????????????
1 ??????????????????
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?
?
?
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?
?
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• ??????????????????????????????????

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????!