The Effect of Center Volume on the Incidence

of Postoperative Complications and their

Impact on Survival after Lung Transplantation

Arman Kilic, MD1, Timothy J. George, MD1, Claude A. Beaty, MD1,

Christian A. Merlo, MD, MPH2, John V. Conte, MD1, Ashish S. Shah, MD1

1Division of Cardiac Surgery and 2Division of Pulmonary and Critical Care Division of Cardiac Surgery and Division of Pulmonary and Critical Care

Medicine

Johns Hopkins Hospital, Baltimore, MDNone of the authors have any relevant financial disclosures.

Background

In lung transplantation (LTx), it is unclear if center volume impacts:

-rates of postoperative complications

-the ability to prevent mortality from such complicationscomplications

Study Aim: To evaluate the effect of center

volume on the incidence of postoperative

complications and their impact on short and

long-term survival following LTx

Methods

Data Source

United Network for Organ Sharing (UNOS) database

Inclusion Criteria

Adults (>17 years) undergoing LTx between 1999 to 2009 in the United States

Exclusion Criteria

Redo LTx

Multivisceral transplants

Data AnalysisAnnual Center Volume

Continuous variable

Categorical variable: equal size patient tertiles

Low: <21.8 LTx/year

Intermediate: 21.8-34.2 LTx/year

High: >34.2 LTx/year

Outcomes

Rates of post-LTx complications (renal failure requiring dialysis, stroke, all-cause reoperation, infection, rejection)

Impact of complications on 90-day, 1-year, and 5-year survival

Baseline Recipient CharacteristicsVariable Low Vol

(<21.8

LTx/yr)

n=4460

Intermed Vol(21.8-34.2

LTx/yr)

n=4227

High Vol(>34.2

LTx/yr)

n=3878

P-

value

Age (years) 51.4 ± 13.0 52.3 ± 12.4 53.1 ± 12.5 <0.001

Female Gender 2086 (47%) 1939 (46%) 1688 (44%) 0.01

Diagnosis 0.03Diagnosis

COPD

IPF

Cystic Fibrosis

Other

1663 (37%)

1269 (29%)

649 (15%)

879 (20%)

1520 (36%)

1283 (30%)

574 (14%)

850 (20%)

1355 (35%)

1190 (31%)

504 (13%)

829 (21%)

0.03

Bridging

ECMO

Mech.

Ventilation

18 (0.4%)

120 (3%)

20 (0.5%)

160 (4%)

38 (1%)

166 (4%)

0.001

<0.001

Serum Creatinine

(mg/dL)

0.91 ± 0.60 0.88 ± 0.44 0.88 ± 0.56 0.01

Baseline Donor and Transplant Characteristics

Variable Low Vol(<21.8

LTx/yr)

n=4460

Intermed Vol(21.8-34.2

LTx/yr)

n=4227

High Vol(>34.2

LTx/yr)

n=3878

P-

value

Age (years) 32.4 ± 13.8 32.4 ± 13.8 34.3 ± 14.7 <0.001

Female Gender 1707 (38%) 1670 (40%) 1623 (42%) 0.004

Trauma as 2297 (52%) 2155 (52%) 1765 (46%) <0.001Trauma as

Mechanism of

Death

2297 (52%) 2155 (52%) 1765 (46%) <0.001

Bilateral LTx 2254 (51%) 2065 (49%) 2728 (70%) <0.001

Ischemic Time

(hours)

4.5 ± 1.6 4.8 ± 1.7 5.4 ± 1.7 <0.001

Rates of Postoperative ComplicationsRate (%)

Low Vol

Intermed Vol

High Vol

*p<0.05

Rate (%)

*

Impact of Complications on SurvivalSurvival (%

)

100

80

60

40

No Comp

40

20

Time (years)0 1 2 3 4 5

Patients At

RiskNo Comp

Renal

Failure

Stroke

Reoperation

Infection

1454 1313 1163 1047 755 378

208 75 39 18 9 6

110 58 39 27 17 15

492 337 284 256 211 152

3205 2432 2134 1888 1549

1084

Impact of Complications on SurvivalSurvival (%

)

100

80

60

40

No Comp

Infection

40

20

Time (years)0 1 2 3 4 5

Patients At

RiskNo Comp

Renal

Failure

Stroke

Reoperation

Infection

1454 1313 1163 1047 755 378

208 75 39 18 9 6

110 58 39 27 17 15

492 337 284 256 211 152

3205 2432 2134 1888 1549

1084

Impact of Complications on SurvivalSurvival (%

)

100

80

60

40

No Comp

Rejection

40

20

Time (years)0 1 2 3 4 5

Patients At

RiskNo Comp

Renal

Failure

Stroke

Reoperation

Infection

1454 1313 1163 1047 755 378

208 75 39 18 9 6

110 58 39 27 17 15

492 337 284 256 211 152

3205 2432 2134 1888 1549

1084

Impact of Complications on SurvivalSurvival (%

)

100

80

60

40

No Comp

Reoperation40

20

Time (years)0 1 2 3 4 5

Patients At

RiskNo Comp

Renal

Failure

Stroke

Reoperation

Infection

1454 1313 1163 1047 755 378

208 75 39 18 9 6

110 58 39 27 17 15

492 337 284 256 211 152

3205 2432 2134 1888 1549

1084

Impact of Complications on SurvivalSurvival (%

)

100

80

60

40

No Comp

Stroke40

20

Time (years)0 1 2 3 4 5

Patients At

RiskNo Comp

Renal

Failure

Stroke

Reoperation

Infection

1454 1313 1163 1047 755 378

208 75 39 18 9 6

110 58 39 27 17 15

492 337 284 256 211 152

3205 2432 2134 1888 1549

1084

Stroke

Impact of Complications on SurvivalSurvival (%

)

100

80

60

40

No Comp

40

20

Time (years)0 1 2 3 4 5

Patients At

RiskNo Comp

Renal

Failure

Stroke

Reoperation

Infection

1454 1313 1163 1047 755 378

208 75 39 18 9 6

110 58 39 27 17 15

492 337 284 256 211 152

3205 2432 2134 1888 1549

1084

Renal Failure

Impact of Complications on SurvivalSurvival (%

)

100

80

60

40

No Comp

Infection

Rejection

Stroke

log-rank p-value <0.001

Reoperation40

20

Time (years)0 1 2 3 4 5

Patients At

RiskNo Comp

Renal

Failure

Stroke

Reoperation

Infection

1454 1313 1163 1047 755 378

208 75 39 18 9 6

110 58 39 27 17 15

492 337 284 256 211 152

3205 2432 2134 1888 1549

1084

Stroke

Renal Failure

Effect of Postoperative Renal Failure on Survival, By Center Volume

Survival (%

)

100

60

40

Low Vol

Intermediate Vol

High Vol

23.7%

20.6%

80

0

Time (years)

0 1 2 3 4 5

Patients At

Risk Low

Intermediate

High

287 92 66 48 38 26

206 68 49 36 24 18

173 63 45 35 29 20

log-rank p-value = 0.0420.6%

16.3%

20

Effect of Reoperation on Survival, By Center Volume

Survival (%

)

100

60

40

Low Vol

Intermediate Vol

High Vol

40.4%

40.2%

80

40

Time (years)

0 1 2 3 4 5

Patients At

Risk Low

Intermediate

High

621 350 282 243 197 140

505 301 265 230 196 133

482 312 264 237 191 136

log-rank p-value <0.00140.2%

31.7%

20

Effect of Postoperative Infection on Survival, By Center Volume

Survival (%

)

100

60

Low Vol

Intermediate Vol

High Vol

52.8%

80

40

Time (years)

0 1 2 3 4 5

Patients At

Risk Low

Intermediate

High

1354 1015 867 748 593 417

1055 779 689 602 503 364

1044 818 729 667 547 363

log-rank p-value <0.001

52.8%

50.6%

43.2%

Effect of Postoperative Rejection on Survival, By Center Volume

Survival (%

)

100

60

40

Low Vol

Intermediate Vol

High Vol

49.1%

40.0%

50.7%

80

40

Time (years)

0 1 2 3 4 5

Patients At

Risk Low

Intermediate

High

284 196 137 89 56 41

191 137 93 62 38 17

285 220 138 90 62 32

log-rank p-value = 0.00940.0%

20

Effect of Postoperative Stroke on Survival, By Center Volume

Survival (%

)

100

60

40

Low Vol

Intermediate Vol

High Vol

38.6%

80

40

Time (years)

0 1 2 3 4 5

Patients At

Risk Low

Intermediate

High

82 34 25 24 20 11

80 47 40 27 21 14

72 34 22 16 14 11

log-rank p-value = 0.20 33.6%

26.8%

38.6%

20

Multivariable Cox Regression AnalysisIn Patients with a Postoperative Complication

Covariate 90-day

MortalityHazard Ratio

1-year

MortalityHazard Ratio

5-year

MortalityHazard Ratio

Decreasing Center

Volume (continuous)

1.01 (1.01-1.02)* 1.01 (1.00-

1.01)*

1.01 (1.00-

1.01)*

Each risk-adjusted for significant

recipient, donor, and transplant variables

in univariate analysis (p<0.2)

*p<0.05

Multivariable Cox Regression AnalysisIn Patients with a Postoperative Complication

Covariate 90-day

MortalityHazard Ratio

1-year

MortalityHazard Ratio

5-year

MortalityHazard Ratio

Decreasing Center

Volume (continuous)

1.01 (1.01-1.02)* 1.01 (1.00-

1.01)*

1.01 (1.00-

1.01)*

Center Volume Center Volume

(categorical)

High

Intermediate

Low

Reference

1.30 (1.30-1.64)*

1.52 (1.22-1.90)*

Reference

1.18 (0.99-1.41)

1.46 (1.24-

1.72)*

Reference

1.03 (0.90-1.18)

1.32 (1.17-

1.50)*

Each risk-adjusted for significant

recipient, donor, and transplant variables

in univariate analysis (p<0.2)

*p<0.05

SummaryEach postoperative complication was associated with an adverse effect on short and longer-term post-transplant survival in LTx

High volume centers did not have significantly lower rates of postoperative complications following LTx

Compared to intermediate volume centers, high volume centers had improved 90-day survival following LTx with a complication

Compared to low volume centers, high volume centers had improved 90-day, 1-year, and 5-year survival following LTx with a complication

Limitations

Did not include institutional factors beyond procedural volume that may impact outcomes due to unavailability of these data in the registry

Study not designed to identify causal relationships between volume and outcomes

Missing data or incorrectly entered data in the UNOS registry

Conclusion

High volume centers do not have the lowest incidences of postoperative complications in LTx

However, in patients with post-LTxcomplications, high volume centers have complications, high volume centers have improved short and long-term survival compared to low volume centers

Identifying and implementing institutional practices that may lead to better management of postoperative complications following LTx in higher volume centers is important

The Effect of Center Volume on the Incidence

of Postoperative Complications and their

Impact on Survival after Lung Transplantation

Arman Kilic, MD1, Timothy J. George, MD1, Claude A. Beaty, MD1,

Christian A. Merlo, MD, MPH2, John V. Conte, MD1, Ashish S. Shah, MD1

1Division of Cardiac Surgery and 2Division of Pulmonary and Critical Care Division of Cardiac Surgery and Division of Pulmonary and Critical Care

Medicine

Johns Hopkins Hospital, Baltimore, MD