In epoch 3, we identified 3509 open cardiac operations in England in children under 1 year for the original study and 4741 such operations in children between 1 year and 15 years; we identified a further 5221 and 6385 operations, respectively, between April 1996 and March 2002. For epoch 3, 5.4% (190 cases) of open operations in children aged under 1 year were carried out in hospitals other than the 11 specialist centres. In epoch 6, this figure declined to 0.2% (five cases).
For children aged 1 to 15, Harefield had a significantly raised mortality in the original analysis (12%, 95% confidence interval 8% to 16%, P < 0.001) in epoch 3, but it has since merged with the Brompton Hospital and their results are combined for consistency over time. However, even their combined mortality remained significantly high (8%, 6% to 10%, P < 0.001) compared with all centres combined in epoch 3. For epoch 5 and 6, Harefield-Brompton were not significantly high. No other centre in epochs 3, 5, or 6 had a significantly raised mortality. The national mortality in this age group also decreased from 5% in epoch 3 to less than 2% in epoch 6.
shows mortality for open operations for children under 1 year in three epochs for the 11 specialist centres in descending order, by total volume of cases. It shows Bristol with a mortality of 29% (21% to 37%, P < 0.001) in epoch 3, but mortality falls to 5% (2% to 9%, P = 0.798) in epoch 5 and 3% (1% to 6%, P = 0.801) in epoch 6. Mortality for all centres combined declined from 12% in epoch 3 to 7% in epoch 5 and 4% in epoch 6. Oxford had a significantly higher mortality than the national average in all three epochs: 19% (12% to 27%, P = 0.010) in epoch 3, 14% (8% to 22%, P = 0.003) in epoch 5, 11% (5% to 18%, P = 0.001) in epoch 6. If Bristol is excluded from the first epoch, Oxford had the highest mortality for all three epochs. However, it too had a downward trend in mortality. The probability of at least one centre having a significantly high mortality in all three epochs by chance alone is less than 0.0002. The probability that Oxford had the highest mortality in epoch 3 was 3% (if Bristol is excluded it was 72%), 48% in epoch 5, and 79% in epoch 6 (see table A on bmj.com
Mortality from open procedures in children aged under 1 year for 11 centres in three epochs; data derived from hospital episode statistics. Centres are listed by descending volumes of cases
Adjustment for procedure by using the 11 open procedure groups made little difference to the pattern of mortality. Oxford remained as the only centre with a significantly high mortality over all three epochs examined, with an odds ratio of 1.75 (1.16 to 2.62, P = 0.007) in epoch 3, 2.11 (1.13 to 3.95, P = 0.019) in epoch 5, and 4.14 (2.12 to 8.09, p < 0.001) in epoch 6, compared with the overall mean of the centres combined (see table B on bmj.com
). The only other centres that had a significantly high odds ratio after adjustment for procedure were Harefield-Brompton (odds ratio 2.04, 95 confidence interval 1.14 to 3.65, P = 0.016) in epoch 5 and Leicester (3.24, 1.88 to 3.95, P < 0.001) also in epoch 5 (see figure A on bmj.com
The proportion of admissions with outcomes unknown improved over time from 5.1% in epoch 3 to 1.4% in epoch 6. However, the proportion varied between centres. For example, in 1995-6, 75% of outcomes in Leicester were unknown, and during epoch 5, 46% of outcomes in Harefield-Brompton were unknown. In Bristol, the proportions unknown fell from 17% in epoch 3 to 1% in epoch 6. Oxford's percentage of operations with an unknown outcome was low (maximum of 1.9% in any of the three epochs examined). We carried out a sensitivity analysis to examine the effect of including admissions with a missing outcome, recoded as discharged alive (figure B on bmj.com
). Oxford remained the only centre with a significantly high mortality in all three epochs, with an odds ratio of 1.80 (1.20 to 2.70, P = 0.004) in epoch 3, 2.25 (1.20 to 4.19, P = 0.011) in epoch 5, and 4.17 (2.14 to 8.13, P < 0.001) in epoch 6. The odds ratio for Harefield-Brompton dropped in epoch 5 to 1.03 (0.58 to 1.81, P = 0.928), indicating that their high mortality in this epoch may have been due to incomplete data.
shows annual mortality for Bristol and for all centres combined, together with total numbers of open operations in children under 1 year. Within all 11 centres, the total number of open operations per year for children under 1 year varied between 732 in 1991-2 and 967 in 1996-7, with no obvious trend; for older children aged between 1 and 15, numbers of operations fell by 11.8% from an average of 1185 per year in epoch 3 to 1045 in epoch 6 (not shown). In epoch 3, Bristol was carrying out an average of around 43 open operations per year on children under 1. This has now increased to 66 patients a year in epoch 6.
Mortality (based on admissions with known outcome) for and number of open operations on children aged under 1 year from April 1991 to April 2002 in 11 English centres; data derived from hospital episode statistics
For Bristol, mortality declined rapidly from 1995. For all centres combined, mortality also fell, but this seems to be a continuous trend throughout the entire period, which is significant (P < 0.01). The small peak in 1995 coincided with some missing data on outcomes, particularly at Leicester, in that year; if missing outcomes are reclassified as “alive when discharged,” the peak disappears.
The shows a comparison of death rates, average annual numbers of procedures, and percentage changes from epoch 3 to epoch 6 for the 11 procedure groups. All show a marked reduction in mortality (between 36% and 91%). The number of Fontan-type operations nearly doubled (94% increase), and their mortality fell from 18% to 1.6%. The number of procedures to correct tetralogy of Fallot (16%) and closure of ventricular septal defect (13%) also rose. Numbers of procedures for total anomalous pulmonary venous drainage and mitral valve procedures remained about the same. Numbers fell for all other procedures listed, ranging from -38% for procedures to correct interatrial transposition of the great arteries to -14% for repair of atrial ventricular septal defects. When we adjusted for procedure for all units combined, mortality was still markedly higher in epoch 3 than in epoch 6, with an odds ratio of 3.5 (2.8 to 4.6).
Table 1 Comparison of mortality (based on admissions with known outcomes), average annual numbers of procedures, and percentage changes from epoch 3 to epoch 6 for 11 defined procedure groups in all centres in England; data derived from hospital episode statistics (more ...)