Keith J Barrington
CHU Sainte Justine
Montréal
Canada
The systematic review
Update of the Cochrane Review
13 RCTs of iNO in preterm infants with respiratory
disease
Varying eligibility, age of use, indications, dose,
duration.
Decided Post Hoc to divide them into 3 groups
Early rescue
Late ‘rescue’
Early routine treatment
Death before discharge
Mortality
None of the individual trials show a statistically
significant reduction.
Meta-analysis of the first 2 trials of early routine use
previously showed potential difference: which was
marginally significant.
Potentially important magnitude of effect, but the
estimate lacked precision.
Adding the data from the abstract of the EUNO trial:
now no difference, RR 0.91 (95% CI 0.74, 1.11)
The early rescue, and later treatment in infants at
risk of BPD groups show no effect on mortality.
BPD among survivors
Death or BPD
Survival without
bronchopulmonary dysplasia
Early rescue treatment studies: no apparent benefit
 subgroup
analysis of Van Meurs et al reduction in
infants > 1 kg birthweight.
Early routine treatment: modest and almost
significant reduction in the combined outcome of
death or BPD RR 0.93, 95% CI 0.86 1.01.
Heterogeneity I2 = 34%, Kinsella + EUNO: no
benefit.
 Subgroup
analysis of Kinsella suggested lower risk
infants (BW >1000 g) had a benefit.
 In Schreiber, subgroup analysis suggested only the less
sick infants (OI less than the median) benefited.
Survival without
bronchopulmonary dysplasia
Ballard et al report: significant benefit of inhaled
nitric in improving survival without BPD.
However the figures given, 165/294 vs. 182/288 are
not significant using RevMan to calculate RR.
Difference due to use of multiple outputation as
planned, a statistical way of correcting for possible
coherence among multiples, (1st of multiples to be
eligible randomized, therefore entered as a cluster,
should be analyzed as a cluster).
 Subgroup
analysis: reduction in combined death or
BPD when started at 7- 14 d, less severe disease may
increase chance of benefit.
Severe IVH or PVL
Brain Injury
Early rescue studies: no significant effect, the
direction of the difference is toward increased
serious IVH
 Not
significant at p<0.05, BUT potential evidence of
harm should always be taken seriously, especially when
there is no evidence of benefit.
Later entry based on BPD risk not expected to affect
IVH incidence.
With the addition of EUNO 2009, early routine use
shows no effect on brain injury, either severe IVH
or combined outcome of severe IVH or PVL.
Heterogeneity I2= 80%
Brain Injury
 Previous analysis suggested a potential benefit in the
early routine treatment group
 EUNO had a higher baseline OI, but a lower mortality
than the other early routine treatment trials, Do these
characteristics explain the difference, or is it just
chance?
Neurodevelopmental impairment
Sensitivity analysis
 I have performed a sensitivity analysis of the early
rescue treatment studies, eliminating the studies with
very early primary outcomes, the studies with
potential crossover, and studies with very small
samples
 Analyses including Innovo, Kinsella 1999, and Van
Meurs 2005, total n=566
 Conclusions are substantially unchanged
Problems with the meta-analysis
 Great variation in study design
 Different eligibility criteria
 Postnatal age
 severity of illness criteria
 Different primary outcomes
 Variable duration of therapy
 Variable doses
IPD meta-analysis
 The standard review and meta-analysis suggested that
there might be significant benefits in certain groups of
infants:
 But no clear indications for therapy were evident
 Don’t want to miss benefits
 Nor potential harms
 In some groups of infants
IPD meta-analysis
 Obtaining original information on all the enrolled
subjects
 Allows:
 Intention to treat analysis
 Consistency of definitions (if enough information was
collected)
 Analyses of subgroups across trials
 Identification of patient characteristics associated with
positive or negative responses
Meta Analysis of Preterm Patients
on inhaled Nitric Oxide Collaboration
Inhaled nitric oxide in preterm infants: a
systematic review and individual patient
data meta-analysis
MAPPiNO aims/objectives
• To determine whether inhaled nitric oxide in preterm infants receiving
•
assisted ventilation improves survival without morbidity, specifically
without:
– CLD
– cerebral injury
– retinal injury
– long-term disability
To determine whether the effects of inhaled nitric oxide differ according to
the risk profile of the patient in terms of:
– gestational age at birth
– severity of illness
– antenatal steroid use
– postnatal age at the time of randomization
– ventilation mode at randomization
– administration of exogenous surfactant
– inhaled nitric dosage and duration of nitric oxide administration
Reasons for IPD in MAPPiNO
• determine whether certain patient or treatment characteristics may
predict benefit from inhaled nitric oxide in the premature infants (patientlevel subgroup analyses)
• define CLD the same way across trials
• aim to analyse all endpoints in all patients in all trials, to avoid biases
associated with selective publication endpoints
• address additional research questions
• improve trial identification, interpretation & dissemination via
collaborative approach
Results: a general approach
• main analyses used log-binomial regression models adjusted for trial
• subgroup analyses used poisson regression models with robust error
variance due to issues with model convergence
• endpoints between siblings from multiple births
• the primary analyses were adjusted for multiple births using the
multiple outputation approach (1000 repetitions)
• sensitivity analysis: generalized estimating equations (GEE) used to
analyse the two main endpoints of interest
Siblings clusters
Distribution of multiples
by treatment group
Trial
n
% multiples
iNO
Placebo
Van Meurs 2005
22
4.9
10 (45.5%)
12 (54.5%)
Srisuparp 2002
2
5.9
0 (0.0%)
2 ( 100%)
Kinsella 2006
130
16.4
61 (46.9%)
69 (53.1%)
Hascoet 2005
14
9.7
10 (71.4%)
4 (28.6%)
Schreiber 2003
26
12.6
11 (42.3%)
15 (57.7%)
Kinsella 1999
2
2.4
1 (50.0%)
1 (50.0%)
Dani 2006
2
5.0
2 ( 100%)
0 (0.0%)
EUNO 2008
152
19.0
71 (46.7%)
81 (53.3%)
Ballard 2006
84
14.4
47 (56.0%)
37 (44.0%)
OVERALL
434
13.1
213 (49%)
221 (51%)
Primary endpoints
• Death or chronic lung disease (CLD) using best available definition
(alive and O2 dependent at 36 weeks PMA if calculable, or trialists’ own
definition)
• Severe adverse neurological event after randomization (intracranial
hemorrhage (IVH) grade III or IV, or cystic periventricular leukomalacia
(PVL) or other pathologies such as periventricular echodensity,
periventricularcysts, ventriculomegaly or hydrocephalus)
Main endpoints assessable for all patients (patients with
no event were censored)
Primary endpoint 1
Death or CLD (Best available definition)
iNO
Placebo
Kinsella 1999
40 / 48 (83%)
27 / 32 (84%)
0.99 (0.81, 1.21)
Srisuparp 2002
6 / 16 (38%)
4 / 18 (22%)
1.59 (0.55, 4.62)
Schreiber 2003
43 / 105 (41%)
56 / 102 (55%)
0.77 (0.57, 1.04)
Hascoet 2005
42 / 61 (69%)
51 / 84 (61%)
1.11 (0.85, 1.43)
INNOVO 2005
54 / 64 (84%)
56 / 62 (90%)
0.93 (0.82, 1.07)
Van Meurs 2005
170 / 224 (76%)
174 / 225 (77%)
0.98 (0.88, 1.09)
Kinsella 2006
292 / 398 (73%)
294 / 395 (74%)
0.99 (0.91, 1.08)
4 / 20 (20%)
8 / 20 (40%)
0.53 (0.19, 1.46)
Ballard 2006
165 / 294 (56%)
184 / 288 (64%)
0.85 (0.74, 0.98)
EUNO 2008
134 / 399 (34%)
137 / 401 (34%)
1.01 (0.83, 1.23)
OVERALL*
954 / 1629 (59%)
992 / 1627 (61%)
0.96 (0.91, 1.01) p=0.095
Trial
Dani 2006
RR (95% CI)
0.2
0.5
1
Favours iNO
2
5
Favours placebo
† Subhedar removed from the analysis as zero cell counts caused model instability.
* χ2 test for heterogeneity p > 0.05
Estimates derived from N=1000 iterations of log-binomial model using multiple outputation method.
Primary endpoint 2
Severe Neurological Event
Trial
iNO
Placebo
RR (95% CI)
Subhedar 1997
1 / 20 (5%)
3 / 22 (14%)
0.37 (0.04, 3.25)
Kinsella 1999
8 / 48 (17%)
7 / 32 (22%)
0.76 (0.31, 1.88)
Srisuparp 2002
1 / 16 (6%)
4 / 18 (22%)
0.27 (0.03, 2.13)
Schreiber 2003
16 / 105 (15%)
25 / 102 (25%)
0.63 (0.35, 1.13)
Hascoet 2005
31 / 61 (51%)
28 / 84 (33%)
1.57 (1.06, 2.34)
INNOVO 2005
5 / 64 (8%)
6 / 62 (10%)
0.81 (0.26, 2.51)
Van Meurs 2005
69 / 224 (31%)
52 / 225 (23%)
1.35 (0.99, 1.83)
Kinsella 2006
117 / 398 (29%)
112 / 395 (28%)
1.04 (0.83, 1.30)
8 / 20 (40%)
7 / 20 (35%)
1.13 (0.50, 2.52)
81 / 399 (20%)
68 / 401 (17%)
1.19 (0.88, 1.61)
315 / 1649 (19%)
286 / 1649 (17%)
Dani 2006
EUNO
OVERALL*
1.12 (0.98, 1.29) p=0.089
0.1
0.2
0.5
1
Favours iNO
† Data from Ballard not available for this analysis.
* χ2 test for heterogeneity p > 0.05
Estimates derived from N=1000 iterations of log-binomial model using multiple outputation method.
2
5
Favours placebo
Primary endpoint 2a
Severe Neurological Event (including death)
Trial
iNO
Placebo
RR (95% CI)
Subhedar 1997
11 / 20 (55%)
8 / 22 (36%)
1.51 (0.77, 2.99)
Kinsella 1999
27 / 48 (56%)
22 / 32 (69%)
0.82 (0.58, 1.16)
Srisuparp 2002
3 / 16 (19%)
5 / 18 (28%)
0.64 (0.18, 2.24)
Schreiber 2003
27 / 105 (26%)
40 / 102 (39%)
0.66 (0.43, 1.01)
Hascoet 2005
42 / 61 (69%)
36 / 84 (43%)
1.61 (1.18, 2.20)
INNOVO 2005
36 / 64 (56%)
41 / 62 (66%)
0.85 (0.64, 1.13)
Van Meurs 2005
143 / 224 (64%)
128 / 225 (57%)
1.13 (0.97, 1.31)
Kinsella 2006
170 / 398 (43%)
171 / 395 (43%)
1.01 (0.86, 1.19)
Dani 2006
10 / 20 (50%)
8 / 20 (40%)
1.25 (0.62, 2.50)
EUNO 2008
110 / 399 (28%)
92 / 401 (23%)
1.22 (0.95, 1.57)
Ballard 2006
22 / 294 (7%)
21 / 288 (7%)
1.03 (0.58, 1.83)
OVERALL*
601 / 1649 (36%) 572 / 1649 (35%)
0.1
1.06 (0.98, 1.16) p=0.149
0.2
Favours iNO
0.5
1
2
5
Favours placebo
† Data on deaths only available from Ballard.
* χ2 test for heterogeneity p=0.050
Estimates derived from N=1000 iterations of log-binomial model using multiple outputation method.
Secondary endpoint 1
Death at any time
iNO
Placebo
RR (95% CI)
Subhedar 1997
11 / 20 (55%)
7 / 22 (32%)
1.73 (0.83, 3.58)
Kinsella 1999
22 / 48 (46%)
17 / 32 (53%)
0.86 (0.55, 1.36)
Srisuparp 2002
2 / 16 (13%)
2 / 18 (11%)
1.06 (0.17, 6.67)
Schreiber 2003
16 / 105 (15%)
22 / 102 (22%)
0.72 (0.39, 1.33)
Hascoet 2005
28 / 61 (46%)
25 / 84 (30%)
1.53 (0.98, 2.39)
INNOVO 2005
33 / 64 (52%)
36 / 62 (58%)
0.89 (0.65, 1.22)
Van Meurs 2005
114 / 224 (51%)
102 / 225 (45%)
1.13 (0.93, 1.37)
Kinsella 2006
78 / 398 (20%)
94 / 395 (24%)
0.85 (0.65, 1.11)
Dani 2006
4 / 20 (20%)
6 / 20 (30%)
0.70 (0.23, 2.10)
Ballard 2006
22 / 294 (7%)
21 / 288 (7%)
1.03 (0.58, 1.83)
EUNO 2008
54 / 399 (14%)
41 / 401 (10%)
1.41 (0.95, 2.09)
OVERALL*
384 / 1649 (23%)
373 / 1649 (23%)
Trial
0.1
1.05 (0.93, 1.17) p=0.45
0.2
Favours iNO
0.5
1
2
5
Favours placebo
* χ2 test for heterogeneity p > 0.05
Estimates derived from N=1000 iterations of log-binomial model using multiple outputation method.
10
Secondary endpoint 3
Death before discharge
RR (95% CI)
iNO
Placebo
Subhedar 1997
10 / 20 (50%)
7 / 22 (32%)
1.57 (0.74, 3.34)
Kinsella 1999
22 / 48 (46%)
17 / 32 (53%)
0.86 (0.55, 1.36)
Srisuparp 2002
2 / 16 (13%)
2 / 18 (11%)
1.06 (0.17, 6.67)
Schreiber 2003
15 / 105 (14%)
20 / 102 (20%)
0.75 (0.39, 1.43)
Hascoet 2005
28 / 61 (46%)
25 / 84 (30%)
1.53 (0.98, 2.39)
INNOVO 2005
32 / 64 (50%)
36 / 62 (58%)
0.86 (0.62, 1.19)
Van Meurs 2005
114 / 224 (51%)
97 / 225 (43%)
1.19 (0.97, 1.46)
Kinsella 2006
78 / 398 (20%)
93 / 395 (24%)
0.86 (0.65, 1.13)
Dani 2006
4 / 20 (20%)
6 / 20 (30%)
0.70 (0.23, 2.10)
Ballard 2006
22 / 294 (7%)
21 / 288 (7%)
1.03 (0.58, 1.83)
EUNO 2008
54 / 399 (14%)
41 / 401 (10%)
1.41 (0.95, 2.09)
OVERALL*
381 / 1649 (23%)
365 / 1649 (22%)
Trial
0.1
1.06 (0.94, 1.19) p=0.32
0.2
Favours iNO
0.5
1
2
5
Favours placebo
* χ2 test for heterogeneity p > 0.05
Estimates derived from N=1000 iterations of log-binomial model using multiple outputation method.
10
Secondary endpoint 4
This analysis assumes that if IVH is missing then IVH =
0 for on study results.
Severe intra-ventricular hemorrhage
Trial
iNO
Placebo
RR (95% CI)
Kinsella 1999
3 / 47 (6%)
2 / 30 (7%)
0.95 (0.17, 5.36)
Srisuparp 2002
1 / 6 (17%)
3 / 5 (60%)
0.28 (0.04, 1.91)
Schreiber 2003
13 / 105 (12%)
19 / 102 (19%)
0.67 (0.34, 1.33)
Hascoet 2005
14 / 61 (23%)
14 / 83 (17%)
1.39 (0.70, 2.78)
INNOVO 2005
2 / 41 (5%)
3 / 32 (9%)
0.52 (0.09, 2.93)
Van Meurs 2005
67 / 189 (35%)
46 /164 (28%)
1.26 (0.93, 1.73)
Kinsella 2006
60 / 398 (15%)
74 / 395 (19%)
0.81 (0.59, 1.12)
3 / 18 (17%)
4 / 19 (21%)
0.84 (0.22, 3.22)
EUNO 2008
71 / 399 (18%)
56 / 401 (14%)
1.27 (0.91, 1.77)
OVERALL*
234 / 1264 (19%)
221 / 1231 (18%)
Dani 2006
0.01
Favours iNO
1.04 (0.88, 1.23) p=0.61
0.1
0.2
0.5
1
2
5
10
Favours placebo
† Subhedar removed from the analysis as zero cell counts caused model instability.
* χ2 test for heterogeneity p > 0.05
Estimates derived from N=1000 iterations of log-binomial model using multiple outputation method.
Data from Ballard not available for this analysis.
Secondary endpoint 4a
Severe intra-ventricular hemorrhage worse than baseline IVH
Trial
INNOVO 2005
iNO
Placebo
RR (95% CI)
2 / 64 (3%)
3 / 62 (5%)
0.65 (0.11, 3.73)
Kinsella 2006
49 / 398 (12%)
63 / 394 (16%)
0.78 (0.55, 1.11)
Hascoet 2005
9 / 51 (18%)
5 / 24 (21%)
1.02 (0.35, 2.96)
Schreiber 2003
6 / 26 (23%)
8 / 13 (62%)
0.37 (0.16, 0.88)
Dani 2006
2 / 14 (14%)
1 / 8 (13%)
1.23 (0.13, 11.48)
EUNO 2008
43 / 300 (14%)
36 / 309 (12%)
1.26 (0.81, 1.94)
OVERALL
111 / 853 (13%)
116 / 810 (14%)
0.87 (0.68, 1.12) p=0.29
0.1
0.2
0.5
1
2
5
10
† Data have been removed where Baseline HUS was taken after start of study gas and also where baseline HUS showed the presence of a Grade 4 IVH
* χ2 test for heterogeneity p > 0.05
Estimates derived from N=1000 iterations of log-binomial model using multiple outputation method.
Data from Van Meurs, Srispuarp, Subhedar, Kinsella 99 and Ballard not available for this analysis.
Secondary endpoint 4a
Severe intra-ventricular hemorrhage adjusted for worse baseline HUS result
Trial
INNOVO 2005
iNO
Placebo
RR (95% CI)
1 / 35 (3%)
2 / 28 (7%)
0.40 (0.04, 4.01)
Kinsella 2006
60 / 360 (17%)
74 / 348 (21%)
0.83 (0.63, 1.09)
Hascoet 2005
12 / 53 (23%)
6 / 25 (24%)
1.06 (0.47, 2.42)
Schreiber 2003
6 / 26 (23%)
8 / 13 (62%)
0.23 (0.08, 0.62)
Dani 2006
3 / 14 (21%)
1 / 8 (13%)
2.31 (0.67, 7.95)
EUNO 2008
46 / 305 (15%)
41 / 312 (13%)
1.10 (0.74, 1.63)
OVERALL
128 / 793 (16%)
132 / 734 (18%)
0.87 (0.71, 1.08) p=0.21
0.01
0.1
0.2
0.5
1
† Data have been removed where Baseline HUS was taken after start of study gas
* χ2 test for heterogeneity p > 0.05
Estimates derived from N=1000 iterations of log-binomial model using multiple outputation method.
Data from Van Meurs, Srispuarp, Subhedar, Kinsella 99 and Ballard not available for this analysis.
2
5
10
Subgroup Analyses
(death or CLD)
Exposure subgroup analyses (Death or CLD)
Overall n (%)
95% CI
Relative
Subgroup
Trials with median Start dose >5ppm
Group
<=5 ppm
iNO
Placebo
732 / 1194 (61%) 739 / 1199 (62%)
>5 ppm
218 / 435 (50%)
Exposure to iNO (trial level) †
Exposure to iNO (individual level)‡
LCL UCL
p
(heterogeneity)*
0.94 1.06 0.889
<0.001
0.83
0.74 0.95 0.005
779 / 1319 (59%) 803 / 1321 (61%)
0.98
0.92 1.04 0.413
>10 ppm
171 / 310 (55%)
188 / 306 (61%)
0.87
0.76 0.99 0.041
Low
353 / 522 (68%)
372 / 525 (71%)
0.95
0.87 1.04 0.254
High
597 / 1107 (54%) 619 / 1102 (56%)
0.96
0.89 1.03 0.216
<105 ppm*days
247 / 452 (55%)
252 / 467 (54%)
1.03
0.92 1.16 0.564
>=105 ppm*days 344 / 639 (54%)
363 / 617 (59%)
0.89
0.82 0.98 0.014
Trials with median Start dose >10ppm <=10 ppm
252 / 428 (59%)
Risk
1.00
P
N.S.
N.S.
N.S.
Data from Subhedar removed from these analyses as zero cell counts caused model instability.
†Srisuparp, Kinsella 2006, EUNO 2008 and Ballard classified as high exposure trials, others classified as low exposure. High exposure was defined as area under the dose-time curve
>= 70 calculated on a trial specific basis.
‡Per-patient exposure analysis only included three trials (Kinsella 06, EUNO 2008 and Ballard). All other trials were excluded either because dose exposure was dependent on
response (INNOVO, Van Meurs, Subhedar, Srisuparp, Hascoet and Kinsella99) or because data on length of time on treatment was not available (Dani, Schreiber). (These data were
not initially requested). Exposure was calculated as AUC and patients were grouped as less than the median (105) or not.
Estimates derived from N=1000 iterations of a poisson regression model with robust error variance using multiple outputation method.
* p value for heterogeneity was calculated as the proportion of the 1000 models which had non-significant p values for the interaction term for subgroup*treatment effect (N.S. =
non significant)
Sensitivity analyses – GEE model
Overall n (%)
Outcome
iNO
Placebo
95% CI
Relative Risk
LCL
UCL
p value
Death or CLD
956 (59%)
993 (61%)
0.96 0.91 1.00
0.0610
Severe Neurological Event
337 (25%)
312 (23%)
1.11 0.98 1.27
0.1072
Death at any time
386 (23%)
374 (23%)
1.03 0.92 1.16
0.5916
Death by 36 weeks
350 (21%)
336 (20%)
1.05 0.93 1.19
0.4504
Death by discharge
383 (23%)
366 (22%)
1.05 0.93 1.17
0.4481
Severe IVH
234 (19%)
221 (18%)
1.04 0.88 1.23
0.6404
Implications
 Further analysis of individual patient data will allow
definition of
 patient characteristics most promising for future studies, and
 most promising treatment protocols, including dose and
duration.
 Based on a single high quality study, later prolonged
treatment with iNO seems to decrease BPD among at-risk
infants, without adverse effects,
 The benefit of early routine treatment which appeared
possible after 2 trials were completed now seems less likely
after EUNO, further analysis of the IPD may help to clarify.
Unanswered questions
 Preterm infants with clear evidence of PPHN exist, is it
reasonable to withhold iNO based on these analyses?


There were 142 babies with ‘pulmonary hypertension’ in the
database, with a small non-significant improvement in the
primary outcome
Diagnostic criteria for PPHN in these infants are uncertain
 Infants with acute deterioration after the early
neonatal period, improvements in oxygenation may
follow iNO, such babies were not eligible for the
majority of these studies.
 Does iNO improve their survival or long term
outcomes?
Implications for further research
 Most promising appears to be infants at high risk for
BPD who are still intubated at 7 days of age
 Treatment should be prolonged and commence at
more than 5 ppm