Secondary outcomes • dcv

Create models

# Fig 2: Respiratory compliance (Cdyn)
cdyn.olv <- rma(yi, vi, data=dat, subset = (outcome1=="Cdyn" & time=="OLV"), method="PM")

# Fig 3: Plateau pressure (Plat)
plat.tlv <- rma(yi, vi, data=dat, subset = (outcome1=="Plat" & time=="TLV"), method="PM")
plat.olv <- rma(yi, vi, data=dat, subset = (outcome1=="Plat" & time=="OLV"), method="PM")

# Fig 4: Peak inspiratory pressure (Peak)
peak.tlv <- rma(yi, vi, data=dat, subset = (outcome1=="Peak" & time=="TLV"), method="PM")
peak.olv <- rma(yi, vi, data=dat, subset = (outcome1=="Peak" & time=="OLV"), method="PM")

# Fig 5: Arterial oxygen pressure (pO2)
po2.tlv <- rma(yi, vi, data=dat, subset = (outcome1=="pO2" & time=="TLV"), method="PM")
# po2.olv <- rma(yi, vi, data=dat, subset = (outcome1=="pO2" & time=="OLV"), method="PM")
# Error when using default options. Fix:
po2.olv <- rma(yi, vi, data=dat, subset = outcome1=="pO2" & time=="OLV", method="PM", control=list(tau2.max=1000))

Collated results

OLV results
	est	p.value	I2
Cdyn	5.5 (3, 7.9)	0.000	89.7
Plateau	-3.5 (-6.5, -0.6)	0.019	87.8
Peak	-4.3 (-5.5, -3.1)	0.000	82.3
PaO2	25.4 (4.3, 46.5)	0.018	92.9

TLV results
	est	p.value	I2
Plateau	-2.7 (-6.1, 0.7)	0.124	92.1
Peak	-2.9 (-4.4, -1.3)	0.000	81.6
PaO2	17.5 (4.7, 30.3)	0.008	34.6

Evidence of effect in all secondary outcomes except Plateau+TLV. These effects persist when the HKSJ modification is used, with the exception of Plateau+OLV (results not shown).

Notes on secondary outcome figures in draft

Figure 3 in paper has different headings compared to Figs 4 and 5.
Fig 4 has TLV first, while Figs 3 and 5 have OLV first.
TLV and OLV data have been mixed up in the document (assuming the Excel sheet is correct)

Forest plots

Fig 2: Respiratory compliance (Cdyn)

Fig 3: Plateau pressure (Plat)

Fig 4: Peak inspiratory pressure (Peak)

Fig 5: Arterial oxygen pressure (pO2)

Attempt to recreate paper results

# Fig 2: Respiratory compliance (Cdyn)
cdyn.olv <- rma(yi, vi, data=dat, subset = (outcome1=="Cdyn" & time=="OLV"), method="REML")

# Fig 3: Plateau pressure (Plat)
plat.tlv <- rma(yi, vi, data=dat, subset = (outcome1=="Plat" & time=="TLV"), method="REML")
plat.olv <- rma(yi, vi, data=dat, subset = (outcome1=="Plat" & time=="OLV"), method="REML")

# Fig 4: Peak inspiratory pressure (Peak)
peak.tlv <- rma(yi, vi, data=dat, subset = (outcome1=="Peak" & time=="TLV"), method="REML")
peak.olv <- rma(yi, vi, data=dat, subset = (outcome1=="Peak" & time=="OLV"), method="REML")

# Fig 5: Arterial oxygen pressure (pO2)
po2.tlv <- rma(yi, vi, data=dat, subset = (outcome1=="pO2" & time=="TLV"), method="REML")
# po2.olv <- rma(yi, vi, data=dat, subset = (outcome1=="pO2" & time=="OLV"), method="PM")
# Error when using default options. Fix:
po2.olv <- rma(yi, vi, data=dat, subset = outcome1=="pO2" & time=="OLV", control=list(tau2.max=1000), method="REML")

Collated results

OLV results
	est	p.value	I2
Cdyn	5.5 (3, 7.9)	0.000	89.3
Plateau	-3.5 (-6.5, -0.5)	0.022	88.2
Peak	-4.3 (-5.6, -3.1)	0.000	82.6
PaO2	25.4 (3.1, 47.8)	0.026	93.8

TLV results
	est	p.value	I2
Plateau	-2.7 (-6.1, 0.7)	0.124	92.1
Peak	-2.9 (-4.4, -1.3)	0.000	82.2
PaO2	18.6 (3.9, 33.2)	0.013	46.0