Diagnostic accuracy of 123 I-FP-CIT SPECT in diagnosing drug-induced parkinsonism: a prospective study.
BACKGROUND
Drug-induced parkinsonism is a major type of parkinsonism in our setting. Symptoms usually disappear after discontinuation of the drug. However, they may persist in patients with a variant known as subclinical drug-exacerbated parkinsonism; early identification of this entity has important prognostic and therapeutic implications. The most widely used complementary test in this diagnosis is single-photon emission computed tomography with ioflupane ((123)I), also known as (123)I-FP-CIT SPECT. The aim of our study is to verify its diagnostic accuracy.


METHODS
We designed a prospective study of patients with drug-induced parkinsonism in which, after discontinuing the drug and undergoing a (123)I-FP-CIT SPECT scan, patients would be monitored for at least 6 months. Patients were categorised as having iatrogenic parkinsonism if symptoms disappeared, or as having subclinical drug-exacerbated parkinsonism if they persisted. Lastly, we verified concordance between the clinical diagnosis and results from the (123)I- FP-CIT SPECT scan.


RESULTS
The sample included 19 patients. The most commonly prescribed drug class was neuroleptic agents. For the diagnosis of both subgroups, (123)I-FP-CIT SPECT showed a sensitivity of 66.7%, specificity and positive predictive value of 100%, a negative predictive value of 86.7%, and a negative likelihood ratio of 0.33.


CONCLUSIONS
Although the study needs to be repeated in a larger sample of patients, (123)I-FP-CIT SPECT is useful in the diagnosis of drug-induced parkinsonism since it is a very precise tool for identifying patients with that illness.
Neurólogo, Hospital Torrecárdenas, Almería, Spain. olivares.je@gmail.com
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Olivares Romero
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Arjona Padillo
D000368:Aged; D000369:Aged, 80 and over; D014150:Antipsychotic Agents / Q000009:adverse effects; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D018476:Hypokinesia / Q000139:chemically induced / Q000000981:diagnostic imaging; D016013:Likelihood Functions; D008297:Male; D008875:Middle Aged; D010302:Parkinson Disease, Secondary / Q000139:chemically induced* / Q000000981:diagnostic imaging*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D014326:Tropanes
D014150:Antipsychotic Agents; D019275:Radiopharmaceuticals; D014326:Tropanes; C087552:2-carbomethoxy-8-(3-fluoropropyl)-3-(4-iodophenyl)tropane