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 USMLE Step 1 Mnemonics Mnemonics, acronyms, reminders, and memorizing tips for the USMLE Step 1.

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#1
10-21-2009
 USMLE Forums Master Steps History: 1+CK+CS+3 Posts: 742 Threads: 137 Thanked 2,462 Times in 441 Posts Reputation: 2565
Odds Ratio

The formula for odds ratio is easily remembered

The years can either be AD or BC
AD = Anno Domini, After christ
BC = Before Christ

The odds ratio
OD = AD/BC

Of course remember that the A cell is always the disease with the risk and then simply cross to the D cell and divide by the other two cells.

So for example in this 2X2 table
The AD cells are in red and the BC cells are in yellow
The A cell is the number of males with stroke.

click image to enlarge

Note in the case of Odds ratio we are measuring the likelihood that a stroke patient is being a male (risk factor) and not the reverse (we are not measuring the probability of getting a stroke if the patient is a male).
 The above post was thanked by: anoop_1198 (07-05-2010), docoftheworld (01-06-2016), docspike (10-22-2009), Mondoshawan (01-22-2011), MSMZ (07-14-2016), Pixie (11-19-2010), riya10 (08-03-2011), Taiwan_Guy (12-06-2010)

#2
12-11-2009
 USMLE Forums Master Steps History: 1+CK+CS+3 Posts: 742 Threads: 137 Thanked 2,462 Times in 441 Posts Reputation: 2565
Caution

I've seen an NBME question that requires the knowledge of this formula
A/C divided by B/D
so the mnemonic of AD/BC is not always useful.
 The above post was thanked by: MSMZ (07-14-2016), Taiwan_Guy (12-06-2010)
#3
01-22-2011
 USMLE Forums Master Steps History: 1+CK+CS Posts: 590 Threads: 31 Thanked 1,233 Times in 411 Posts Reputation: 1257

Quote:
 Originally Posted by rasheed I've seen an NBME question that requires the knowledge of this formula A/C divided by B/D so the mnemonic of AD/BC is not always useful.
Isn't that the same thing in the end?
A/C divided by B/D
=
A/C times D/B
=
AD/BC

I think your mnemonic is pretty good
 The above post was thanked by: madeha shahid (06-09-2012), Sabio (01-22-2011)

#4
04-28-2011
 USMLE Forums Newbie Steps History: --- Posts: 6 Threads: 3 Thanked 23 Times in 3 Posts Reputation: 33

"Not in the case of Odds ratio we are measuring the likelihood that a stroke patient is being a male (risk factor) and not the reverse".

what do you mean by" not the reverse"??
#5
04-28-2011
 USMLE Forums Master Steps History: 1+CK+CS+3 Posts: 742 Threads: 137 Thanked 2,462 Times in 441 Posts Reputation: 2565

Quote:
 Originally Posted by life9 "Not in the case of Odds ratio we are measuring the likelihood that a stroke patient is being a male (risk factor) and not the reverse". what do you mean by" not the reverse"??
Odds Ratio: measuring the odds of a risk factor when you already have the disease, i.e. you already have stroke, what's the likelihood that it was caused by male sex. It starts with the disease and ends with risk factor.

While Relative Risk and Attibutable Risk: it starts with the risk factor and ends with the disease, i.e. if you are male then what's the likelihood you'll get stroke.
 The above post was thanked by: dr.tahaiqbal (12-17-2013), life9 (04-29-2011), madeha shahid (06-09-2012), mayankkaushal (05-23-2013), MSMZ (07-14-2016)

 Tags Biostatistics-Epidemiology

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