Skip to main content

Table 2 Mortality data at 1 year reported for THA (n/N) vs HA (n/N) in 3 reviews

From: A case study of binary outcome data extraction across three systematic reviews of hip arthroplasty: errors and differences of selection

Study BMJ Cochrane HTA Comments
Dorr 1986 [22] 3/39 vs 4/50 NR NA (event data for each arm NR) Error:
Dorr reports 7 deaths across both arms; BMJ review categorises this as 3 and 4 in each arm [10]
Skinner 1989 [17] 21/91 vs 24/89 18/80 vs 27/100 20/89 vs 25/91 Error and Selection difference:
(1-year data) As Table 1 for these data
Ravikumar 2000 [18]
(13-year data)
Baker 2006 [12] NR NR NR NA
Keating 2006 [11] 4/69 vs 11/111 4/69 vs 6/69 4*/69 vs 6/69 Selection difference:
As Table 1
Blomfeldt 2007 [9] 4/60 vs 3/60 4/60 vs 3/60 4/60 vs 3/60 Identical
Macaulay 2008 [23] 1/17 vs 5/23 NR NR Selection difference:
BMJ analyses reported 6-month data as 1 year data; Cochrane, HTA and Liang [7] all omit it from the 1-year analysis; Cochrane analysis uses these data for 6-month follow-up only. It is unclear when the additional deaths reported for up to 2 years (4/17 vs 7/23) occurred. They may have occurred in the 6–12 month period.
Mouzopoulos 2008 [8] 10/43 vs 13/43 6/43 vs 6/43 6/39 vs 6/38 Selection difference:
Denominators: HTA applied an intention-to-treat analysis, excluding 4 from THA arm (2 data lost; 2 not satisfy inclusion criteria) and 5 from HA arm (none satisfied trial’s inclusion criteria), as they did not satisfy the study’s inclusion criteria and no follow-up data were collected. [13] If these are included, then explicit best and worst case analyses perhaps should have been performed, with imputations explained [14]
  4/24 errors =17% 2/16 errors =13%   4-6 analysed studies =a/B vs c/D =16 or 24 variables:
10/24 selection differences = 42% 4/16 selection differences = 25%
  1. *Liang has 5/69 here: an error. Otherwise Liang has the same data as the HTA. THA,Total Hip Arthroplasty; HA, Hemiarthroplasty; NR, Not Reported; NA, Not Applicable. Findings are given in bold.
\