Table 1

Characteristics of included studies

StudyLocationDesignNumberSex (male/female (%))Age
(years)
Ever smokerFollow-up (years)Clinical domainSerological domainMorphological domainUIP pattern*OutcomeComparison†Statistical method
Chung et al
201637
USARetrospective cohort136
(49.3/50.7)
63.5±10.970/136 (51.5)All-cause mortalityIPAFCox
Oldham et al
201638
USARetrospective cohort14469/75 (47.9/52.1)63.2±11.079/144(54.5) –71/144 (49.3)132/144 (91.7)123/144 (85.4)77/141 (54.6)All-cause mortalityIPAFCox
IPAF versus IPFLog rank
IPAF-UIP versus IPFLog rank
IPAF versus CTD-IP§Log rank
IPAF-nonUIP versus CTD-IP§Log rank
Adegunsoye et al
201739
USARetrospective cohort8441/43 (48.8/51.2)60.1±10.047/84 (56.0) –36/- (44.4)79/84 (94.0)62/84 (73.8)All-cause mortalityIPAFCox
Ahmad et al
201740
FranceRetrospective cohort5729/28 (50.9/49.1)64.4±14.016/47 (34.0)1.5 (median)27/57 (47.3)53/57 (93.0)45/57 (78.9)16/54 (29.6)All-cause mortalityIPAFCox
IPAF versus IPFLog rank
IPAF-UIP versus IPAF-nonUIPLog rank
Collins et al
201741
USARetrospective cohort158/7 (53.3/46.7)54.6±11.87/15 (46.7) –5/15 (33.3)Change of PFTIPAF versus IPFTukey
IPAF versus CTD-IP¶Tukey
IPAF-UIP versus IPAF-nonUIPStudent t
Dai et al
201842
ChinaRetrospective cohort17778/99 (44.1/55.9)60.2±12.934/177 (19.2) –36/177 (20.3)163/177 (92.1)169/177 (95.5)8/177 (4.5)All-cause mortalityIPAFCox
IPAF versus IPFLog rank
Lim et al
201943
KoreaRetrospective cohort5419/35
(35.2/64.8)
67.9±10.515/54 (27.8) –17/54 (31.5)49/54 (90.7)44/54 (81.5)15/54 (27.8)All-cause mortalityIPAF versus IPFCox
IPAF-UIP versus IPFLog rank
IPAF versus CTD-IP**Chi-squared
Ito et al
201744
JapanRetrospective cohort9841/57 (41.8/58.2)67.5 (59.0–76.0)‡38/98 (38.8)4.6 (median)98/98 (100)98/98 (100)0/98 (0)All-cause mortalityIPAFCox
CTD incidenceIPAFDescriptive
Mejía et al
201745
MexicoRetrospective cohort348/26 (23.5/76.5)53.2±9.3 –34/34 (100)1/34 (2.9)All-cause mortalityIPAF versus CTD-IP††Log rank
Kelly and
Moua 201746
USARetrospective cohort10140/61 (39.6/60.4)56.9±14.331/101 (30.7) –77/101 (76.2)87/101 (86.1)96/101 (95.0)19/101 (18.8)All-cause mortalityIPAF-UIP versus IPFLog rank
IPAF-UIP versus IPAF-nonUIPLog rank
Yoshimura et al
201847
JapanRetrospective cohort3219/13 (59.4/40.6)63.4±12.618/32 (56.2)5.6
(mean)
17/32 (53.1)23/32 (71.9)31/32 (96.9)13/32 (40.6)All-cause mortalityIPAF versus CFIPCox
IPAF-UIP versus IPFLog rank
IPAF-NSIP versus iNSIPLog rank
Kim et al
201948
KoreaRetrospective cohort10948/61
(44.0/56.0)
60.6±11.540/109 (36.7) –49/109 (45.0)88/109 (80.7)100/109 (91.7)40/109 (36.7)All-cause mortalityIPAFCox
IPAF-UIP versus IPFLog rank
IPAF versus CTD-IP‡‡Log rank
IPAF-UIP versus CTD-UIP§Log rank
IPAF versus IIP§§Log rank
IPAF-nonUIP versus IIP-nonIPF¶¶Log rank
Change of PFTIPAF versus IIP§§Log rank
CTD incidenceIPAFDescriptive
  • Data are expressed as mean±SD or count/a total number (percent) unless otherwise specified.

  • *All studies were based on the finding of HRCT scan excluding two studies (Kelly and Moua,46 Kim et al 48), which additionally considered pathological findings and another study (Adegunsoye et al 39), which was based on pathological findings alone.

  • †‘IPAF’ indicating a comparative analysis between IPAF with and without potential prognostic factors.

  • ‡Median (range).

  • §No detailed explanation for CTD-IP or CTD-UIP.

  • ¶Scleroderma spectrum disease and RA were the most common, accounting for 37.1% and 22.9%, respectively and a radiological UIP pattern on HRCT was present in 33% of the total number of patients.

  • **Underlying CTDs were composed of 46 cases of RA, 18 of SSc, 6 of Sjögren syndrome, 5 of inflammatory muscle disease and 1 of SLE.

  • ††All cases of underlying CTDs were idiopathic inflammatory myopathy spectrum disease and no UIP pattern was confirmed on HRCT.

  • ‡‡Underlying CTDs were composed of 65 cases of RA, 25 of PM/DM, 24 of Sjögren syndrome, 20 of SSc, 7 of MCTD, 6 of overlap syndrome and 2 of SLE.

  • §§IIPs consisted of 333 cases of IPF, 36 cases of NSIP, 35 cases of COP and 73 cases of unclassifiable IP.

  • ¶¶IIPs-nonIPF consisted of 36 cases of NSIP, 35 cases of COP and 73 cases of unclassifiable IP.

  • CFIP, chronic fibrosing interstitial pneumonia; COP, cryptogenic organising pneumonia; CTD-IP, connective tissue disease-associated interstitial pneumonia; HRCT, high-resolution computed tomography; IIP, idiopathic interstitial pneumonia; iNSIP, idiopathic non-specific interstitial pneumonia; IP, interstitial pneumonia; IPAF, interstitial pneumonia with autoimmune features; IPF, idiopathic pulmonary fibrosis; MCTD, mixed connective tissue disease; PFT, pulmonary function test; PM/DM, polymyositis/dermatomyositis; RA, rheumatoid arthritis; SLE, systemic lupus erythematosus; SSc, sysytemic sclerosis; UIP, usual interstitial pneumonia.