Saturday, May 26, 2012

PPD Interpretation

Classification of the Tuberculin Skin Test Reaction

An induration of 5 or more millimeters is considered positive in
-HIV-infected persons
-A recent contact of a person with TB disease
-Persons with fibrotic changes on chest radiograph consistent with prior TB
-Patients with organ transplants
-Persons who are immunosuppressed for other reasons (e.g., taking the equivalent of >15 mg/day of prednisone for 1 month or longer, taking TNF-a antagonists)
An induration of 10 or more millimeters is considered positive in
-Recent immigrants (< 5 years) from high-prevalence countries
-Injection drug users
-Residents and employees of high-risk congregate settings
-Mycobacteriology laboratory personnel
-Persons with clinical conditions that place them at high risk
-Children < 4 years of age
- Infants, children, and adolescents exposed to adults in high-risk categories
An induration of 15 or more millimeters is considered positive in any person, including persons with no known risk factors for TB. However, targeted skin testing programs should only be conducted among high-risk groups.
CDC (Center for Disease Control and Prevention)

Friday, May 25, 2012


Normal values

75-gram 2 Hour oral glucose tolerance test
  • Fasting    60 -100 mg/dL
  • 1 hr:        less than 200 mg/dL
  • 2 hrs:      less than 140 mg/dL. 
140 - 200 mg/dL = Impaired glucose tolerance
> 200 mg/dL = Diabetes

50-gram 1 hour oral glucose tolerance test
  • 1 hour: < or =140 mg/dL
if >140, do
100-gram 3 hour oral glucose tolerance test
  • Fasting: less than 95 mg/dL
  • 1 hour: less than 180 mg/dL
  • 2 hour: less than 155 mg/dL
  • 3 hour: less than 140 mg/dL
2 or more abnormal values = GDM

Random facts (statistics)

Differential loss to follow up: Attrition. A type of selection bias found in cohort studies

Reliability: repeatability of a measure

Validity: absence of bias

Bias: systematic error

Selection bias: deferential access to study population (from selection process, respodents no longer available at the end, attrition etc)

Confounding: unfair comparison

Volunteer bias: type of selection bias, the tendency for one's health to influence decision to participate in a study

Information bias: occurs when the means of obtaining information from cases and controls differ

Hazards ratio, Relative risk

HR = Probability of event in treatment grp/Probability of event in control group

RR = Probability of event in treatment grp/Probability of event in control group

Exactly! same formular!

Hazard ratio is actually a type of Relative risk (a.k.a Risk ratio)

The difference?
HR is instantaneous while RR is culmulative.
RR can only be calculated at the end of the study while HR can be calculated at different points in time. Hazard ratios are calculated using the survival analysis technique. This keeps track of the number of subjects who haven't had the event (e.g death) at a particular time.

Again, HR is an estimate of RR

HR of 1 means the rate of occurrence of the event in treatment/intervention grp is same as in control/placebo grp

HR >1  means event occurs more in the intervention grp

HR <1  means event occurs less in the intervention grp

To convert a HR to probability,

Probability of event occurring = HR/1+ HR

So, HR of 1 is a probability of 50%. A 50:50 chance, i.e treatment and placebo grps are the same in terms of outcome

Wednesday, May 23, 2012

Regarding asthma treatment

Practice recommendations
  • Every patient with persistent asthma, regardless of disease severity, should use a daily controller medication.

  • Consider an inhaled corticosteroid (ICS) first when choosing controller medications for long-term treatment of mild, moderate, and severe persistent asthma in adults and children. Leukotriene modifiers, cromolyn, and nedocromil may be considered as alternative, not preferred, controller medications for patients with persistent asthma.

  • Long-acting β2-adrenergic agonists should not be used as monotherapy.

  • Long-term use of ICSs within labeled doses is safe for children in terms of growth, bone mineral density, and adrenal function; nonetheless, asthma should be monitored and ICS therapy stepped down to the lowest effective dose.

  • Low-to medium-dose ICSs are not associated with the development of cataracts or glaucoma in children, but high cumulative lifetime doses may slightly increase the prevalence of cataracts in adults and elderly patients.

  • ICSs are recommended for use in pregnant women with asthma; budesonide is the only ICS rated Pregnancy Category B.
 From:The Journal of Family Practice

Oral corticosteroids are used in acute exercerbations not for long term management.

Neonatal conjuctivitis

"Silver eyed on day 1
Gon home within 7 days
only to return after a week
with trachs on his chlam
and again in a month
when the herpes showed up!"

Day 1:Chemical conjuctivitis
Day 3-7: Gonococcal
After wk 1: Chlamydia
After 3wks: Herpes 

Monday, May 21, 2012


7 days to go!

Wao! excited actually...

Kaplan q bank scores were initially lower than I expected but have improved now, I have a simulated exam to take when today dawns but first, I've got to catch some sleep!