dromlakhani Shared decision‑making for AEDs with weight‑effect estimates
STEP 1 — Gather Information
Collect patient seizure type, frequency, comorbidities, current weight/BMI, pregnancy potential, and patient‑reported concerns about weight change. Gather published weight‑effect data for candidate AEDs (e.g., valproate + ≈ 5‑10 % baseline gain, lamotrigine ≈ 0 % change, topiramate ≈ ‑5 % loss, zonisamide ≈ ‑4 % loss, gabapentin/pregabalin ≈ + 5‑7 % gain, carbamazepine ≈ + 2‑4 % gain).
STEP 2 — Rule In / Rule Out
Is weight gain a salient concern for this patient (e.g., baseline overweight/obesity, prior weight‑sensitive comorbidities, or explicit patient worry)?
- Yes → proceed to weight‑effect stratification.
- No → select AED based primarily on seizure efficacy and tolerability; document that weight effect was considered and deemed low priority.
STEP 3 — Classify or Stratify
Stratify candidate AEDs into three categories using the guideline’s weight‑effect estimates:
- Weight‑loss: felbamate, topiramate, zonisamide (average ‑3 % to ‑6 % over 6‑12 mo).
- Weight‑neutral: lamotrigine, levetiracetam, phenytoin (average change ‑1 % to +1 %).
- Weight‑gain: gabapentin, pregabalin, valproic acid, vigabatrin, carbamazepine (average + 4 % to +10 %).
Match each category to the patient’s seizure syndrome efficacy profile.
STEP 4 — Decide
Choose the AED that offers adequate seizure control while aligning with the patient’s weight preference, using shared decision‑making: present the quantitative weight‑change estimate (e.g., “lamotrigine is expected to produce <1 % weight change, whereas valproate may cause ~7 % gain over 6 months”) and elicit the patient’s values. Document the discussion, the selected agent, and the agreed‑upon weight‑effect expectation.
Clinical Guardrails / Mimics / Pitfalls
Do not ignore weight concerns in patients with obesity or a history of weight‑sensitive conditions; do not assume all AEDs have equivalent weight effects; avoid prescribing a weight‑gain AED without discussing lower‑impact alternatives; do not rely solely on efficacy data when weight is a priority; refrain from using valproate in women of childbearing potential without counseling on teratogenicity and weight gain.
Concrete Clinical Example
A 28‑year‑old woman with new‑onset focal epilepsy, BMI 28 kg/m², expresses worry about gaining weight. The clinician explains that lamotrigine is weight‑neutral (~0 % change), topiramate may cause ~5 % weight loss, and valproate often leads to ~7 % weight gain over six months. After discussing seizure efficacy and side‑effect profiles, she chooses lamotrigine. The visit note records the shared decision, the quantitative weight estimates provided, and the chosen AED.
Source: Pharmacological Management of Obesity, Endocrine Society, 2015, DOI:10.1210/jc.2014-3415