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Posted by on May 28, 2008 in Ethics, Neurology, Pediatrics

Young-Geier Autism Study: What the—? (Part 3)

Young-Geier Autism Study: What the—? (Part 3)

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This post represents the third installment of my review of the study by Young et al, which links exposure to Thimerosal-containing vaccines with autism. Previous posts on the subject can be found here, here, here, and here.

Results

Table 3 presents the rate ratios and 95% confidence intervals for each diagnosis assuming a µg increase in mercury exposure from Thimerosal-containing vaccines administered from birth to 7 months and birth to 13 months. It was observed that there were significantly increased rate ratios for the neurodevelopmental disorders of autism, autism spectrum disorder (ASD), hyperkinetic syndrome of childhood (attention deficity disorder/attention deficity hyperactivity disorder), developmental disorder/learning disordernot otherwise specificied, disturbance of emotions specific to childhood and adolescence, and tics following additional Hg exposure from Thimerosal-containing childhood vaccines…By contrast, no significantly increased rate ratios for the control disorders of pneumonia, congenital anomalies, and failure to thrive were observed with increasing Hg exposure from Thimerosal containing vaccines.

The rate ratios, given a 100-µg increase in vaccine-related ethylmercury exposure, are reproduced below from Young et al’s Table 3:

Condition

Rate Ratio (95% CI),
Birth-7 Months

Rate Ratio (95% CI),  Birth-13 Months

Neurodevelopmental

 

 

Autism

2.87 (1.19, 6.94)

2.62 (1.15, 6.01)

Autism spectrum

2.44 (1.16, 5.10)

2.20 (1.10, 4.40)

Hyperkinetic syndrome

3.15 (2.38, 4.17)

4.51 (3.48, 5.84)

Developmental disorder/ learning disorder—not otherwise specified

1.73 (1.08, 2.75)

1.81 (1.17, 2.80)

Disturbance of emotions

2.27 (1.36, 3.80)

2.91 (1.81, 4.68)

Tics

3.39 (1.64, 6.79)

4.11 (2.12, 7.94)

Control

 

 

Pneumonia

0.98 (0.86, 1.11)

0.92 (0.82, 1.04)

Congenital anomalies

0.62 (0.34, 1.14)

0.57 (0.33, 1.00)

Failure to thrive (FTT)

1.05 (0.74, 1.47)

0.92 (0.67, 1.27)

There’s little to say about these numbers, other than they have to be taken on faith, which is a dubious proposition in my opinion. The rate (or risk) ratios for the neurodevelopmental disorders are very high, suggesting (in some cases) a several-hundred-fold increased risk for a neurodevelopmental disorder with what is really a very small (ie, 100-µg) increase in ethylmercury exposure. The 95% confidence intervals for the neurodevelopmental disorders are also exceptionally wide, especially when compared with those for the control conditions. The following graphs of the rate ratios and 95% CIs illustrate this point.

Birth-7 Months

Rate_ratios_7_mos.PNG

Birth-13 Months

Rate_ratios_13_mos.PNG

Also, given these data, couldn’t it be concluded (although a P value is not provided) that a 100-ug increase in vaccine-related ethylmercury exposure reduces the risk of congenital anomalies by approximately 40%?

Next: Discussion.

bmartin (1130 Posts)

A native East Tennessean, Barbara Martin is a formerly practicing, board-certified neurologist who received her BS (psychology, summa cum laude) and MD from Duke University before completing her postgraduate training (internship, residency, fellowship) at the Hospital of the University of Pennsylvania in Philadelphia. She has worked in academia, private practice, medical publishing, drug market research, and continuing medical education (CME). For the last 3 years, she has worked in a freelance capacity as a medical writer, analyst, and consultant. Follow Dr. Barbara Martin on and Twitter.