Onderzoek naar diagnostische tests
Study reference Study characteristics Patient characteristics Index test (test of interest) Reference test Controle (gouden standaard) Follow-up Outcome measures and effect size Comments

Colon, 2009

Type of study:

Retrospective diagnostic test accuracy study

 

Setting:

Out-patient clinic of Kempenhaeghe: a tertiary referral centre for epilepsy

 

Country: The Netherlands

 

Source of funding: The study was partly based on a project paid for by the “zorgverzekeraars Nederland”

Inclusion criteria: Age >6yr, suspicion of neocortical localization-related epilepsy and an inconclusive routine EEG

 

Exclusion criteria: high suspicion of nonepileptic seizures on clinical grounds, prior EEG with epileptiform discharges and medication change before routine MEG could be performed, presence of intracranial metals, pacemakers or pumps and inability to cooperate.

 

N= 51

 

Mean age ± SD:

43.4 yr (range 16-72)

 

Sex: 48.1% M (n=26) / 51,9% F (n=28)

 

Other important characteristics:

EEG performed to confirm clinical diagnosis: 29 pt

EEG performd to localize the irritative zone: 22 pt

Routine EEG after sleep deprivation according to standard clinical practice.

 

Vs.

 

MEG 2 to 5 weeks after EEG (to recover from sleep deprivation) with a 151-channel whole head MEG system with a base length of 5 cm.

 

For patients for whom the main question concerned the localization of the irritative zone, magnetic source imaging was performed.

 

MEG files were anonimized and rated without a prior knowledge of the outcome of previous EEGs. Rating was performed both by a skilled technician and a skilled certified clinical neurophysiologist independently and thereafter discussed to reach consensus.

Cut-off point(s): Epileptiform activity was defined as a sharp transient different from background activity with an epileptiform morphology and a plausible spatial distribution.

 

MEG findings were categorized as “epileptiform” (multiple spikes <70 milliseconds, clearly distinguishable from the background), “suggestive for epilepsy” (recurrent but less-pronounced ground), “other abnormalities” and “no abnormalities”.

 

Vigilance was also recorded in EEG as well as in MEG and divided into wake, drowsy and sleep.

 

Results from EEG were categorized in the same way as were MEG results.

The final diagnosis from the clinician based on all available information (including results from EEG, sleep deprivated EEG and MEG) taken from the patient charts.

 

To formulate a hypothesis on the diagnosis, semiology was studied as described by the treating physician, including localization and if possible lateralization.

 

Cut-off point(s):

Clinician’s assessments were categorized as “ epilepsy” (including probable epilepsy, leading to the decision to start antiepileptic drug treatment), “ no epilepsy”  and “ uncertain” .

Endpoint of follow-up:

Results of MEG, sleep deprivated EEG and final diagnosis.

 

For how many participants were no complete outcome data available?

N (%): 0

Final diagnosis of epilepsy: 37/51 (73%)

 

Affirmed by MEG (epileptiform activity): 15/37 (40.5%)

Affirmed or supported by MEG: 27/37 (73%)

Not supported by MEG: 7/37 (18.9%)

 

Affirmed by EEG: 11/37 (29.7%)

Affirmed or supported by EEG: 23/37 (62%)

Not supported by EEG: 11/37 (29.7%)

 

None of the patients with findings on EEG after sleep deprivation had a negative MEG.

 

Difference in diagnostic gain between MEG and sleep deprivated EEG after inconclusive routine EEG = not significant

- fault in data reporting (patient characteristics about 54 patients, while only 51 were included according to text)

- final diagnosis is not necessarily the right diagnosis (patients had no surgery enabling to check diagnosis)

- relevant outcomes as sensitivity are not reported, only raw data

 


Checklist

* 2 Is the reference standard likely to correctly classify the target condition?
- Final diagnosis was used as a reference standard, there was no definitive proof (no surgery or other outcome results of treatment were available to check the validity of diagnosis)

* Level of evidence
- Only raw data reported, no sensitivity scores calculated
- Small study population (n=51)
- Retrospective study

McGonigal, 2004

Type of study:

Diagnostic test accuracy study 

 

Setting: Regional epilepsy centre

 

Country: UK

 

Source of funding: NR

Inclusion criteria: Clinical assessment that attacks may occur

 

Exclusion criteria: patients already included into a RCT

 

N= 143

 

Mean age ± SD:

Range 14-75

 

Sex: 32.9%M (N= 47) 67.1%F (N=96)

Short term Video EEG (SVEEG) with a 16 channel EEG with single channel electrocardiogram and simultaneous digital video-recording. Average recording duration was 40-50 min. SVEEG recordings were performed within 4 h – 12 wk after referral, or sooner depending on indication.

 

If PNES were suspected, simple suggestion techniques were used. If an attack was recorded, it was shown to an eyewitness, to confirm whether typical

 

Cut-off point(s): A diagnosis was made only if the recorded attack and EEG findings were unequivocal, and consistent with the available history.

No reference test

Endpoint of follow-up:

Diagnosis

 

Duration of follow-up:

18 months

 

For how many participants were no complete outcome data available?

N: 0

Diagnosis:

PNES: 51/143

Epilepsy: 7/143

Other (not epilepsy): 14/143

Inconclusive: 11/143

No attack recorded: 60/143

- incomplete data reporting

- does not give an answer to the usefulness of SVEEG in the diagnosis of attack disorders, since there is no reference  test.