title: The importance of baseline viral load when assessing relative efficacy in treatment-naïve HBeAg-positive chronic hepatitis B: a systematic review and network meta-analysis.
abstract: BACKGROUND
  To date no network meta-analysis (NMA) has accounted for baseline variations in viral load when assessing the relative efficacy of interventions for chronic hepatitis B (CHB). We undertook baseline-adjusted and unadjusted analyses using the same data to explore the impact of baseline viral load (BVL) on CHB treatment response.
  
  
  METHODS
  We searched Embase, Medline, Medline in Process and the Cochrane CENTRAL databases for randomised clinical trials (RCTs) of monotherapy interventions at licensed doses for use in CHB. Search strategies comprised CHB disease and drug terms (a combination of controlled vocabulary and free text terms) and also a bespoke RCT filter.The NMA was undertaken in WinBUGs using fixed and random effects methods, using data obtained from a systematic review. Individual patient data (IPD) from an entecavir clinical trial were used to quantify the impact of different baseline characteristics (in particular undetectable viral load (UVL) at 1 year) on relative treatment effect. Study level mean baseline values from all identified studies were used. Results were generated for UVL and presented as relative risks (RRs) and 95% credible intervals (CrIs) using entecavir as reference treatment.
  
  
  RESULTS
  Overall, for all eight relevant interventions we identified 3,000 abstracts. Following full text review a total of 35 (including the contents of six clinical study reports) met the inclusion critera; 19 were in hepatitis B e antigen (HBeAg)-positive patients and 14 of the 19 contained outcome information of relevance to the NMA.Entecavir and tenofovir studies had heterogeneous patient populations in terms of BVL (mean values 9.29 and 8.65 log10 copies/ml respectively). After adjusting UVL for BVL using an informative prior based on the IPD analysis, the difference between entecavir and tenofovir was not statistically significant (RR 1.27, 95% CrI 0.96 to 1.47-fixed effects). A similar conclusion was found in all sensitivity analyses. Adjusted tenofovir results were more consistent with observed clinical trial response rates.
  
  
  CONCLUSIONS
  This study demonstrates the importance of adjusting for BVL when assessing the relative efficacy of CHB interventions in achieving UVL. This has implications for both clinical and economic decision making.
authors.affiliation: Oxford Outcomes Ltd, Seacourt Tower, West Way, Oxford OX2 0JJ, UK. stuart.mealing@oxfordoutcomes.com.
authors.forename: Stuart
authors.initials: S
authors.lastname: Mealing
authors.forename: Isabella
authors.initials: I
authors.lastname: Ghement
authors.forename: Neil
authors.initials: N
authors.lastname: Hawkins
authors.forename: David A
authors.initials: DA
authors.lastname: Scott
authors.forename: Benedicte
authors.initials: B
authors.lastname: Lescrauwaet
authors.forename: Maureen
authors.initials: M
authors.lastname: Watt
authors.forename: Mark
authors.initials: M
authors.lastname: Thursz
authors.forename: Pietro
authors.initials: P
authors.lastname: Lampertico
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Mantovani
authors.forename: Edith
authors.initials: E
authors.lastname: Morais
authors.forename: Bruno
authors.initials: B
authors.lastname: Bregman
authors.forename: Michel
authors.initials: M
authors.lastname: Cucherat
mesh_terms: D000998:Antiviral Agents / Q000627:therapeutic use*; D006513:Hepatitis B e Antigens / Q000097:blood; D019694:Hepatitis B, Chronic / Q000188:drug therapy / Q000821:virology*; D006801:Humans; D016896:Treatment Outcome; D019562:Viral Load
chemical_list: D000998:Antiviral Agents; D006513:Hepatitis B e Antigens