Thursday, March 25, 2010

Getting It Right: Being Smarter about Clinical Trials

The PSA test provides some important object lessons. It can detect a broad spectrum of prostate cancers. However, prostate cancers are a heterogeneous group—ranging from rapidly progressing and aggressive to slowly progressive or nonprogressive. Treating the last group may lead to the erroneous conclusion that these patients were “cured” by screening and treatment. If unscreened and untreated, these same men might simply have gone on to die from other causes—at the same point in time. Early diagnosis based on screening may also lead to the erroneous assumption that screening increases true survival time, since survival is measured from the time of diagnosis—longer in the case of the screening diagnosis compared with the time when the patient becomes symptomatic (the “lead time” bias).

Movie Night

The Business of Being Born

I'm about 20 minutes into this and it's right on the money.

No pun

This shows my experience being trained to deliver babies and practicing Obstetrics on my own for 3 years in the hospital. It really IS a fight to fend off the cascade of interventions from the culture of the OB floor.

Great movie for perspective on the medical system.

Digging up More old Prevnar data

So here's where the original study that got prevnar approved had some pneumonia data and 2 years after the vaccine has been approved based on this study (without this data included) 2 years after prevnar has been standard of care for the nation's infants.

In per protocol follow-up of children given PCV, first episodes of all clinically diagnosed pneumonia were reduced by 4.3% [95% confidence interval (CI), -3.5, 11.5%, P = 0.27]

That stuff after 4.3% says "we don't know when adjusting for random chance if the vaccine prevents all cause clinically diagnosed pneumonia or not. "

Then they go on to talk about how that number exploded to 17% as they continued the study. I'll get the original and see what's in there. This is only the abstract.

Of course there's other studies of the effectiveness and longer term effects on children ( see Invasive Pneumococcal Disease Caused by Nonvaccine Serotypes Among Alaska Native Children With High Levels of 7-Valent Pneumococcal Conjugate Vaccine Coverage)

Where the levels of IPD dropped 67% then rebounded with replacement serotypes with 19A being the most common. The overall rate of IPD was still lower at the end of this longer study but there was replacement disease and the serotype 19A has gone on to develop quite a reputation for causing multi-drug resistant infections in children.

But the original study in California got the stuff approved, so let's see what was going on down there.