PANDAS: horse or zebra?

[peglem]

Did anybody read this editorial? I don't have access to the full text, but from the title, I'd sure like to know what it says!

 

http://www.ncbi.nlm.nih.gov/pubmed/1979412...p;ordinalpos=40

[P_Mom]

Neurology. 2009 Oct 20;73(16):1256-63. Epub 2009 Sep 30.

 

Streptococcal infection, Tourette syndrome, and OCD: is there a connection?

Schrag A, Gilbert R, Giovannoni G, Robertson MM, Metcalfe C, Ben-Shlomo Y.

 

Department of Clinical Neurosciences, Royal Free Campus, Institute of Neurology, University College London, London, UK. a.schrag@medsch.ucl.ac.uk

 

Comment in:

 

Neurology. 2009 Oct 20;73(16):1252-3.

 

BACKGROUND: A causal relationship of common streptococcal infections and childhood neuropsychiatric disorders has been postulated. OBJECTIVE: To test the hypothesis of an increased rate of streptococcal infections preceding the onset of neuropsychiatric disorders. METHODS: Case-control study of a large primary care database comparing the rate of possible streptococcal infections in patients aged 2-25 years with obsessive-compulsive disorder (OCD), Tourette syndrome (TS), and tics with that in controls matched for age, gender, and practice (20 per case). We also examined the influence of sociodemographic factors. RESULTS: There was no overall increased risk of prior possible streptococcal infection in patients with a diagnosis of OCD, TS, or tics. Subgroup analysis showed that patients with OCD had a slightly higher risk than controls of having had possible streptococcal infections without prescription of antibiotics in the 2 years prior to the onset of OCD (odds ratio 2.59, 95% confidence interval 1.18, 5.69; p = 0.02). Cases with TS or tics were not more likely to come from more affluent or urban areas, but more cases lived in areas with a greater proportion of white population (p value for trend = 0.05). CONCLUSIONS: The present study does not support a strong relationship between streptococcal infections and neuropsychiatric syndromes such as obsessive-compulsive disorder and Tourette syndrome. However, it is possible that a weak association (or a stronger association in a small susceptible subpopulation) was not detected due to nondifferential misclassification of exposure and limited statistical power. The data are consistent with previous reports of greater rates of diagnosis of Tourette syndrome or tics in white populations.

 

PMID: 19794128 [PubMed - indexed for MEDLINE]

[peglem]

I was looking for somebody who has read the PANDAS: horse or zebra editorial, by DL Gilbert & R Kurlan...

 

Is it saying that PANDAS is common or rare? Are these authors naysayers?

 

I know the study you posted claims PANDAS is almost nonexistant.

[Buster]

Did anybody read this editorial? I don't have access to the full text, but from the title, I'd sure like to know what it says!

 

http://www.ncbi.nlm.nih.gov/pubmed/1979412...p;ordinalpos=40

 

I posted about the study here: http://www.latitudes.org/forums/index.php?...&hl=gilbert

 

Let me know if you'd like the actual paper.

 

Buster

[thereishope]

Gilbert is the confused neurologist I've referred to in the past that my son has seen. He says one thing, writes another, etc, etc.

[peglem]

Okay, thanks. No further probing necessary.

[momto2pandas]

I would be interested in the text of the editorial, too, but haven't read it. In case anyone doesn't know, the horse/zebra thing comes from the question, "if you hear the sound of hoofs, should you think 'horse' or should you think 'zebra'?" Basically, the idea is that you would think horse and most of the time it is a horse, i.e. common symptoms are probably caused by common causes. I believe that the primary immune folks have zebras as their "mascot" and wear zebra T-shirts, because so many of them had been written off as neurotic or having other common issues before being properly diagnosed.

 

I think that the below case-control study is kind of stupid in its premise. The idea isn't that PANDAS kids necessarily have been more likely to have had a strep infection in the past, but that they have unusual, autoimmune reactions to those strep infections. You could easily have one kid who has gotten 10 infections and no OCD, and another who only had one strep infection and got OCD - but that doesn't mean that there is no connection between strep and OCD in that latter individual; it just means that not all kids have the same susceptibility.

 

 

Neurology. 2009 Oct 20;73(16):1256-63. Epub 2009 Sep 30.

 

Streptococcal infection, Tourette syndrome, and OCD: is there a connection?

Schrag A, Gilbert R, Giovannoni G, Robertson MM, Metcalfe C, Ben-Shlomo Y.

 

Department of Clinical Neurosciences, Royal Free Campus, Institute of Neurology, University College London, London, UK. a.schrag@medsch.ucl.ac.uk

 

Comment in:

 

Neurology. 2009 Oct 20;73(16):1252-3.

 

BACKGROUND: A causal relationship of common streptococcal infections and childhood neuropsychiatric disorders has been postulated. OBJECTIVE: To test the hypothesis of an increased rate of streptococcal infections preceding the onset of neuropsychiatric disorders. METHODS: Case-control study of a large primary care database comparing the rate of possible streptococcal infections in patients aged 2-25 years with obsessive-compulsive disorder (OCD), Tourette syndrome (TS), and tics with that in controls matched for age, gender, and practice (20 per case). We also examined the influence of sociodemographic factors. RESULTS: There was no overall increased risk of prior possible streptococcal infection in patients with a diagnosis of OCD, TS, or tics. Subgroup analysis showed that patients with OCD had a slightly higher risk than controls of having had possible streptococcal infections without prescription of antibiotics in the 2 years prior to the onset of OCD (odds ratio 2.59, 95% confidence interval 1.18, 5.69; p = 0.02). Cases with TS or tics were not more likely to come from more affluent or urban areas, but more cases lived in areas with a greater proportion of white population (p value for trend = 0.05). CONCLUSIONS: The present study does not support a strong relationship between streptococcal infections and neuropsychiatric syndromes such as obsessive-compulsive disorder and Tourette syndrome. However, it is possible that a weak association (or a stronger association in a small susceptible subpopulation) was not detected due to nondifferential misclassification of exposure and limited statistical power. The data are consistent with previous reports of greater rates of diagnosis of Tourette syndrome or tics in white populations.

 

PMID: 19794128 [PubMed - indexed for MEDLINE]

[Buster]

The editorial is quite short 1 1/2 pages . The substance of the editorial is that symptoms of sydenham chorea are clearly different from other conditions. Their argument is that SC is separable from the "herd of those with Tourette syndrome" whereas PANDAS is not well separated. They complain that the clinical presentation of dramatic waxing/waning in PANDAS is not a bright stripe -- since "regular tics and OCD often dramatically wax, [and] streptococcal infections and symptoms are ubiquitous."

 

Then they go on to say that even if PANDAS were a common horse and didn't stand out from the herd of other OCD/tic illnesses by symptoms, then one should be able to see a relationship between an antcedent streptococcal infection and the occurence of tic or OCD diagnoses.

 

They then reference their own prior longitudinal study of checking older children with Tourette Syndrome (i.e., not clear they had a PANDAS kid in the mix) where they did not find any OCD variance and found no correlation of tic symptoms with GABHS. So rather than realize that they selected the wrong group of horses (i.e., took no OCD-only children and chose those with long term tics and checked kids who were treated for GABHS infection (meaning that they did not study untreated GABHS but only treated GABHS)... sigh, so many things wrong with their study.)

 

They finally conclude, "Current evidence indicates that ... GABHS infection does not seem to be an important etiologic factor and therefore not an appropriate target for assessment or therapy" and "if you hear hooves, we can safely act like they are horses" (by which they mean that if you see tics or OCD treat as you would any other tics/OCD).

 

I hate these types of editorials -- they are clever -- so they'll get repeated, and wrong, because the conclusion is not justified by the proported evidence.

 

Those writing these editorials do not know of the pathogenesis of "horses" and weren't part of the separation of "zebras". They don't know what causes the symptoms they are seeing. There is just not sufficient evidence to conclude "if we hear hooves, we can safely act like there are horses." They could conclude that if we hear hooves with no OCD symptoms, then the likelihood is they are horses.

 

If there is a separate pathogenesis PANDAS, then you can't conclude you should "act like they are horses" -- this would be like treating all chest pain the same way. Chest pain is a symptom not a cause. It could be a heart attack, indigestion, or the knife stuck in there.... I hate retrospective studies -- especially one where there were almost no throat cultures.

 

Grrrr...

 

Buster

 

 

 

I would be interested in the text of the editorial, too, but haven't read it. In case anyone doesn't know, the horse/zebra thing comes from the question, "if you hear the sound of hoofs, should you think 'horse' or should you think 'zebra'?" Basically, the idea is that you would think horse and most of the time it is a horse, i.e. common symptoms are probably caused by common causes. I believe that the primary immune folks have zebras as their "mascot" and wear zebra T-shirts, because so many of them had been written off as neurotic or having other common issues before being properly diagnosed.

 

I think that the below case-control study is kind of stupid in its premise. The idea isn't that PANDAS kids necessarily have been more likely to have had a strep infection in the past, but that they have unusual, autoimmune reactions to those strep infections. You could easily have one kid who has gotten 10 infections and no OCD, and another who only had one strep infection and got OCD - but that doesn't mean that there is no connection between strep and OCD in that latter individual; it just means that not all kids have the same susceptibility.

 

 

Neurology. 2009 Oct 20;73(16):1256-63. Epub 2009 Sep 30.

 

Streptococcal infection, Tourette syndrome, and OCD: is there a connection?

Schrag A, Gilbert R, Giovannoni G, Robertson MM, Metcalfe C, Ben-Shlomo Y.

 

Department of Clinical Neurosciences, Royal Free Campus, Institute of Neurology, University College London, London, UK. a.schrag@medsch.ucl.ac.uk

 

Comment in:

 

Neurology. 2009 Oct 20;73(16):1252-3.

 

BACKGROUND: A causal relationship of common streptococcal infections and childhood neuropsychiatric disorders has been postulated. OBJECTIVE: To test the hypothesis of an increased rate of streptococcal infections preceding the onset of neuropsychiatric disorders. METHODS: Case-control study of a large primary care database comparing the rate of possible streptococcal infections in patients aged 2-25 years with obsessive-compulsive disorder (OCD), Tourette syndrome (TS), and tics with that in controls matched for age, gender, and practice (20 per case). We also examined the influence of sociodemographic factors. RESULTS: There was no overall increased risk of prior possible streptococcal infection in patients with a diagnosis of OCD, TS, or tics. Subgroup analysis showed that patients with OCD had a slightly higher risk than controls of having had possible streptococcal infections without prescription of antibiotics in the 2 years prior to the onset of OCD (odds ratio 2.59, 95% confidence interval 1.18, 5.69; p = 0.02). Cases with TS or tics were not more likely to come from more affluent or urban areas, but more cases lived in areas with a greater proportion of white population (p value for trend = 0.05). CONCLUSIONS: The present study does not support a strong relationship between streptococcal infections and neuropsychiatric syndromes such as obsessive-compulsive disorder and Tourette syndrome. However, it is possible that a weak association (or a stronger association in a small susceptible subpopulation) was not detected due to nondifferential misclassification of exposure and limited statistical power. The data are consistent with previous reports of greater rates of diagnosis of Tourette syndrome or tics in white populations.

 

PMID: 19794128 [PubMed - indexed for MEDLINE]

[peglem]

Thank you, Buster. I appreciate your commentary!