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Satyendra Dhar MD

@DharSaty

Feb 12, 2023

Sensitivity and Specificity:

The question is:👇

In a study, 200 of the 300 people with the disease had a positive test & 500 of the 700 people without the disease had a negative test

HOW TO DO CALCULATIONS: 👇

The first & important step is to prepare:

🙋‍♂️2 x 2 TABLE

1/n

From the 👇table we gather that:

True Positive (TP) = 200
False Positive (FP) = 200
False Negative (FN) = 100
True Negative (TN) = 500

2/n

Sensitivity =
TP/TP+FN x 100
= 200/200+100 x100
= 66.7%

Specificity =
TN/FP+TN X 100
= 500/200+500 X 100
= 71.4%

Positive Predictive Value (PPV)=
TP/TP+FP X 100
=200/200+200 X 100
= 50%

Negative Predictive Value (NPV)=
TN/FN+TN X 100
= 500/500+100 X 100
= 83.3%

3/n

Read 5 tweets

Satyendra Dhar MD

@DharSaty

Feb 10, 2023

Sensitivity and Specificity ??

what is sensitivity?
what is specificity?

👇👇

Well, both are measures of a test’s 👉validity.

👉Remember:

🙋‍♂️SNOUT
SeNsitive test with a Negative result rules OUTthe disease

🙋‍♂️SPIN
Specific test with a Positive result rules INthe disease.

1/n

👉Sensitivity

✔️Ability to detect people who do have the disease.
✔️Used for screening or ruling out disease.
✔️TP/TP+FN (%)

👉Specificity

✔️Ability to detect people who do not have the disease.
✔️Used to confirm or Rule in the existence of a disease.
✔️TN/FP+TN (%)
2/n

Clinical use:

👉HIGHLY SENSITIVE test should be used first, which guarantees the detection of all cases of the disease.

Followed by👇

👉HIGHLY SPECIFIC test to eliminate the false-positive results.

Question time:👇👇

3/n

Read 4 tweets

Satyendra Dhar MD

@DharSaty

Apr 1, 2022

Duration of Antibiotic Therapy
Deciding on the duration of antimicrobial therapy for an infection is neither straightforward nor simple. 👇
#MedTwitter #MedEd #USMLE #FOAMed #hospitalist #mbbs #medicine #doctor
#medschool #MedStudentTwitter #medstudent #TwitterRx
🔽👇🔽🔽👇

/1

Most ID guidelines are based- either expert opinions or evidence-based medicine. Historically, duration of ABX Rx were based on arbitrary extension of days(magic numbers like 7, 10 & 14 days) rather than on reliable evidence with the main aim to ⬇️ failures & avoid underRx.

/2

There is growing evidence to support for shorter courses. It is important for prescribers to be up to date with best practices. Duration of therapy plays a pivotal role in antimicrobial stewardship programme within the global effort to optimize antibiotic use &⬇️resistance.

/3

Read 26 tweets

Satyendra Dhar MD

@DharSaty

Mar 31, 2022

LASIX and HF
👇👇👇👇
#MedTwitter #MedEd #USMLE #FOAMed #hospitalist #mbbs #medicine #doctor

👇👇👇

/1

4-chloro-N-(2-furyl-methyl)-5-sulfamoyl-anthranilic acid, member of the sulfa’s. Potent natriuretic drug, inhibits Na+-K+-2Cl− cotransporter in the ascending limb of the loop of Henle.
Direct Vd effects results in its therapeutic effectiveness in the Rx of acute pulm edema.

/2

Vasodilation leads to reduced responsiveness to vasoconstrictors, such as angiotensin II and noradrenaline, and decreased production of endogenous natriuretic hormones with vasoconstricting properties.

/3

Read 15 tweets

Satyendra Dhar MD

@DharSaty

Mar 26, 2022

@ImproveDX

Pseudomonas aeruginosa (PA):

Gram-negative bacillus found widely in nature, in soil and water.
/1

#MedTwitter #MedEd #USMLE #FOAMed #hospitalist #mbbs #medicine #doctor @ImproveDX

The genus Pseudomonas >140 species,> saprophytic & >25 species are associated with humans. Most known to cause disease in humans are associated with opportunistic infections.

⬆️ MR : ⬇️ host defenses, resistance to ABX & production of extracellular enzymes & toxins.
/2

Often found in water in sinks & can contaminate respiratory equipment, which can serve as an environmental reservoir, especially in ICUs. Is the most serious pathogen causing ventilator-associated pneumonia & remains the most important pathogen in patients with CF.
/3

Read 15 tweets

Satyendra Dhar MD

@DharSaty

Mar 26, 2022

Ischemic penumbra:
The part of an Ac ischemic stroke that is at risk of progressing to infarction but is still salvageable if reperfused. Located around an infarct core which represents the tissue which has already infarcted or is going to infarct regardless of reperfusion.
/1

In this small cohort, the penumbra system was able to revascularize the site of primary occlusion in all of the treated subjects enrolled into the study, resulting in a revascularization rate of 100%.
/2

ajnr.org/content/29/7/1…

Saving the penumbra is the goal of acute ischaemic stroke therapy. Reperfusing the brain before infarct growth is completed will salvage the residual penumbra and reduce final infarct size.

academic.oup.com/brain/article/…

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