Recovery Trajectories After Lumbar Fusion Stratified by Baseline Patient-Reported Outcomes Measurement Information System Physical Function Disability Levels

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Figure 1
Adjusted cumulative incidence curve depicting time to minimal clinically important difference achievements for all patients.
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Figure 2
Adjusted cumulative incidence curve depicting time to minimal clinically important difference achievements stratified by baseline patient-reported outcomes measurement information system-physical function disability.

Table 1

Baseline patient and operative characteristics by preoperative PROMIS-PF disability level.

Characteristic	Mild (n = 20)	Moderate (n = 92)	Severe (n = 32)	P
Demographics
Age, y	66.0 ± 8.7	64.7 ± 11.2	67.2 ± 11.0	0.515
BMI	29.6 ± 6.3	31.4 ± 5.5	31.1 ± 4.9	0.423
Sex				0.329
Women	16 (80.0)	58 (63.0)	20 (62.5)
Men	4 (20.0)	34 (37.0)	12 (37.5)
Non-white race	7 (35.0)_a	10 (10.9)_b	7 (21.9)_a,b	0.021
ASA ≥3	6 (30.3)	52 (56.5)	17 (53.1)	0.098
CCI score	2.6 ± 1.8	2.5 ± 1.4	3.0 ± 1.8	0.293
Prior spine surgery
Laminectomy	2 (10.0)	23 (25.0)	5 (15.6)	0.233
Fusion	2 (10.0)	10 (10.9)	2 (6.2)	0.749
Procedure type
PLF	11 (55.0)	44 (47.8)	17 (53.1)	0.779
PLIF/TLIF	9 (45.0)	48 (52.2)	15 (46.9)
Primary diagnosis
Pseudarthrosis/hardware failure	0 (0)	4 (4.3)	0 (0)	0.766*
Degenerative disc disease	5 (25.0)	24 (26.1)	8 (25.0)	0.990
Degenerative spondylolisthesis	10 (50.0)	58 (63.0)	19 (59.4)	0.552
Spinal stenosis	5 (25.0)_a	6 (6.5)_b	5 (15.6)_a,b	0.035*
Symptom type
Axial only	1 (5.0)	8 (8.7)	3 (9.4)
Radicular only	2 (10.0)	8 (8.7)	4 (12.5)	0.943
Axial and radicular	17 (85.0)	76 (82.6)	25 (78.1)
Symptom frequency
Intermittent	6 (30.0)	14 (15.2)	5 (15.6)	0.274
Constant	14 (70.0)	78 (84.8)	27 (84.4)	0.274
Change in symptoms
No change/better	13 (65.0)	46 (50.0)	11 (34.4)	0.090
Worse	7 (35.0)	46 (50.0)	21 (65.6)	0.090
Symptom duration
≤1 y	5 (25.0)	41 (44.6)	17 (53.1)	0.134
>1 y	15 (75.0)	51 (55.4)	15 (46.9)	0.134

Abbreviations: ASA, American Society of Anesthesiologists; BMI, body mass index (kg/m²); CCI, Charlson Comorbidity Index; PLF, posterolateral fusion; PLIF/TLIF, posterior lumbar interbody fusion/transforaminal lumbar interbody fusion; PROMIS-PF, patient-reported outcomes measurement information system-physical function.
Note: Data are presented as mean ± SD or n (%). Statistically significant values at P < 0.05 are in boldface.
Subscripts denote post-hoc Bonferroni adjusted comparisons. Different letters denote significant differences between groups.
*Denotes Fisher's Exact test

Table 2

Patient-reported and clinical outcomes by preoperative PROMIS-PF disability level.

Variable	Mild (n = 20)	Moderate (n = 92)	Severe (n = 32)	P
PROMIS-PF
Baseline PF	40.7 ± 7.1_a	34.3 ± 2.8_b	26.2 ± 3.7_c	<0.001
Last (1 y) postoperative PF	45.1 ± 7.3_a	40.6 ± 7.9 _a,b	38.4 ± 7.9_b	0.011
MCID
Early	5 (25.0)_a	34 (37.0)_a,b	19 (59.4)_b	0.027
Late	4 (20.0)	20 (21.7)	3 (9.4)	0.300
Never	11 (55.0)	38 (41.3)	10 (31.2)	0.237
Any MCID	9 (45.0)	54 (58.7)	22 (68.8)	0.237
Days to MCID (achievers only)	142.4 ± 70.0_a	112.2 ± 76.4 _a,b	72.8 ± 57.2 _b	0.027
Days to MCID (including censored non-achievers)	248.3 ± 116.7_a	194.1 ± 126.7 _a,b	134.6 ± 119.0_b	0.005
Clinical outcome
LOS hours	47.8 ± 29.8 _a,b	50.8 ± 27.9_b	68.0 ± 37.7_a	0.016
LOS days	1.7 ± 1.2 _a,b	1.8 ± 1.2_b	2.5 ± 1.6_a	0.018
SNF discharge	0 (0)_a,b	0 (0)_b	3 (9.4)_a	0.013*
30-d ED return	1 (5.0)	10 (10.9)	0 (0)	0.122
30-d readmission	0 (0)	4 (4.3)	5 (15.6)	0.051
Repeat 1-y fusion	3 (15.0)	7 (7.6)	2 (6.2)	0.494
Other 1-y reoperation	1 (5.0)	5 (5.4)	3 (9.4)	0.708

Abbreviations: ED, emergency department; LOS, length of stay; MCID, minimal clinically important difference; PROMIS-PF, patient-reported outcomes measurement information system-physical function; SNF, skilled nursing facility.
Note: Data are presented as mean ± SD or n (%). Statistically significant values at P < 0.05 are in boldface.
Subscripts denote post-hoc Bonferroni-adjusted comparisons. Different letters denote significant differences between groups.
*Denote Fisher's Exact test

Table 3

Univariate Cox models: predictors of time to MCID achievement.

Predictor	HR	95% CI	P
Demographics
Age	0.99	0.97–1.01	0.169
BMI	1.00	0.96–1.04	0.987
Sex	1.22	0.78–1.90	0.375
Non-white race	0.67	0.36–1.27	0.223
ASA ≥3	0.57	0.37–0.88	0.011
CCI score	0.85	0.73–0.98	0.025
Prior spine surgery
Laminectomy	1.02	0.61–1.72	0.941
Fusion	0.80	0.37–1.73	0.566
Procedure type
PLF	1.15	0.75–1.76	0.522
Primary diagnosis
Pseudarthrosis/hardware failure	0.69	0.17–2.80	0.603
Degenerative disc disease	1.04	0.63–1.72	0.885
Degenerative spondylolisthesis	0.98	0.63–1.52	0.911
Spinal stenosis	1.10	0.57–2.13	0.777
Symptom type
Axial only	1.28	0.62–2.66	0.506
Radicular only	0.86	0.40–1.87	0.706
Axial and radicular	0.95	0.54–1.66	0.862
Symptom frequency
Constant	0.63	0.37–1.06	0.081
Change in symptoms
Worse	1.10	0.72–1.69	0.657
Symptom duration
>1 y	0.94	0.61–1.44	0.772
PROMIS-PF
Baseline PF	0.95	0.92–0.98	0.005
Baseline disability
Mild (40+)	0.57	0.28–1.13	0.109
Moderate (30–40)	0.88	0.56–1.36	0.557
Severe (<30)	1.81	1.11–2.95	0.017

Abbreviations: ASA, American Society of Anesthesiologists Score; BMI, body mass index; CCI, Charlson Comorbidity Index; MCID, minimal clinically important difference; PLF, posterolateral fusion.
Note: Statistically significant values at P < 0.05 are in boldface.

Table 4

Multivariate linear and logistic regression: time to MCID and early MCID achievement.

Predictors	β/OR	95% CI	P
Linear regression (β): days to MCID achievement (MCID achievers only)
ASA ≥3	−13.1	−45.9 to 19.8	0.430
CCI score	9.5	−2.6 to 21.6	0.122
Severe disability	−47.4	−84.4 to –10.5	0.013
Linear regression (β): days to MCID achievement (all patients)
ASA ≥3	28.0	−15.8 to 71.7	0.208
CCI score	14.8	0.56 to 29.0	0.042
Severe disability	−77.0	−127.8 to −26.2	0.003
Logistic regression (OR): early MCID achievement
ASA ≥3	0.64	0.30–1.35	0.236
CCI score	0.76	0.59–0.98	0.038
Severe disability	2.95	1.23–7.04	0.015

Abbreviations: ASA, American Society of Anesthesiologists Score; CCI, Charlson Comorbidity Index; MCID, minimal clinically important difference.
Note: P values < 0.05 in bold.

Table 5

Multivariate Cox proportional hazard model: predictors of time to MCID.

Predictors	HR	95% CI	P
Demographics
ASA ≥3	0.55	0.34–0.91	0.018
CCI score	0.88	0.75–1.03	0.118
PROMIS-PF baseline disability
Moderate (30–40) vs mild	1.90	0.86–4.22	0.113
Severe (<30)
vs mild	3.52	1.48–8.42	0.005
vs moderate	1.85	1.10–3.12	0.020

Abbreviations: ASA, American Society of Anesthesiologists Score; CCI, Charlson Comorbidity Index; MCID, minimal clinically important difference.
Note: P values < 0.05 in bold.