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Table 1 Definition of variables

From: Psychotropic and anti-epileptic drug use, before and after surgery, among patients with low-grade glioma: a nationwide matched cohort study

Variable

Definition

Index date

Date of surgery

Index year

Year of surgery

Use of anti-epileptics (AED)

Purchase of ATC class N03A (anti-epileptics), except those mainly used for pain: N03AX12 (Gabapentin) and N03AX16 (Pregabalin), within the last 90 days.

History of seizure/epilepsy

Purchase of ATC class N03A (anti-epileptics), except N03AX12 and N03AX16 and/or ICD-10: G40 (epilepsy) and/or registered “seizure” as symptom in SBTR. All within one year prior to index date.

Use of antidepressants

Purchase of ATC: N06A (antidepressants) within the last 90 days.

History of depression

ATC: N06A and/or ICD-10: F20.4 (post-schizophrenic depression), F31.3-F31.5 (bipolar affective disorder), F32 (depressive episode), F33.0-F33.3 (recurrent depressive disorder), F34 (persistent mood disorders), F41.2 (mixed anxiety and depressive disorder), F43.2 (adjustment disorders). All within one year prior to index date.

Use of sedatives

Purchase of ATC: N05B (anxiolytics) and N05C (hypnotics and sedatives) within the last 30 days.

History of anxiety and/or sleeping difficulties

ATC: N05B and/or N05C (except N05CD08) and/or ICD-10: G47 (sleeping disorders), F40 (phobias), F41.0 (anxiety disorders), F41.1, F41.3, F41.8, F41.9, F42.0 (obsessive disorders), F42.1, F42.2, F42.8, F42.9. All within one year prior to index date.

Elixhauser comorbidity index

According to index. The conditions removed from the index due to possible association with diagnosis of LGG were: G40, G41 (Status epilepticus), R56 (Convulsions), R47 (Dysphasia/aphasia), C70–72 (Malignant tumour in central nervous system). Cases and controls were provided with a score from 0 to 30 based upon comorbid categories present or not. We report categories as 0, 1, 2, ≥3. The ICD-10 data used to classify comorbidity was taken from the NPR during the year prior to index date.