2.5 Data extraction and management
Two independent review authors (PA & SM) screened the titles and
abstracts of identified studies and full texts of potentially eligible
studies. Disagreements were resolved by discussion or arbitration by a
third author (AM). Duplicates were removed both automatically using
Endnote and by manual screening.
The two review authors independently extracted data from eligible
studies into a piloted, standardised data extraction form (Microsoft
Excel). If consensus was not reached, disagreements were resolved by
discussion first and then arbitration by a third author (AM). Data
extraction included bibliometric data (e.g. authors, title, country),
study characteristics (e.g. setting, sample size, target population,
funding, conflicts of interest), participant characteristics (e.g. age,
sex, diagnosis, baseline number of gabapentinoids prescribed),
interventions and controls (gabapentinoid type, dose, duration,
intervention design and aim), co-interventions (e.g. use of other
therapies), outcome data (pre/post gabapentinoid prescribing rates,
adverse events including withdrawal symptoms (with descriptors and
related characteristics), withdrawals from the intervention,
patient-reported outcomes (pre/post intervention pain intensity (e.g.
Visual Analogue Scale) and quality of life (e.g. Hamilton Anxiety Rating
Scale, EuroQol-5-Dimension scores), barriers to deprescribing (for
patients and clinicians) and data completeness (i.e. percentage of
missing data, how missing data were handled).
Serious adverse events were defined as events that were life
threatening, such as those that resulted in death, hospitalisation,
significant incapacity, congenital anomaly, or birth defects. Adverse
events were defined as non-serious adverse events, such as side effects
e.g. dizziness, drowsiness, confusion, dry mouth. Successful cessation
of gabapentinoid therapy was defined as ceasing the medication without
switching to another high-risk medication from another inappropriate
drug class (e.g. benzodiazepine or opioid).
Follow-up time points for outcomes were categorised as either short (≤ 3
months), intermediate (> 3 but < 12 months) or
long (≥ 12 months) term. The short-term follow-up was considered the
primary outcome time point. If multiple time points fell within the same
period, the one-time point closest to 7 weeks, 6 months and 12 months
for each follow up period was used.
If relevant data were missing, the authors were contacted to request
clarification or additional data (e.g. in the case where only an
abstract was available (27, 28). If data were not available within the
text, means and standard deviations (SDs) were estimated from graphs and
figures, if available. If SDs were not reported, we attempted to
estimate them from the confidence intervals (CIs) or other measures of
variance. If SDs were missing for follow-up outcomes, we used the SD for
that outcome at baseline.