Productivity benefits of minimally invasive surgery in patients with chronic sacroiliac joint dysfunction

Figures & data

Table 1 Demographic and health status characteristics of NHIS and SIJ fusion trial participants

Category	Subcategory	NHIS (N=31,543)	SIJ fusion (N=265)		NSM (N=43)
			Baseline	6 months	Baseline	6 months
Age	20–29 yrs	18%	2%	2%	2%	2%
	30–39 yrs	19%	14%	14%	9%	9%
	40–49 yrs	18%	27%	27%	19%	19%
	50–59 yrs	19%	32%	32%	35%	35%
	60–69 yrs	16%	21%	21%	28%	28%
	70–79 yrs	10%	4%	4%	7%	7%
Sex	Female	55%	71%	71%	58%	58%
	Male	45%	29%	29%	42%	42%
Health status	Excellent	27%	3%	7%	7%	7%
	Very good	32%	29%	38%	21%	26%
	Good	27%	40%	37%	44%	44%
	Fair	11%	22%	15%	23%	19%
	Poor	4%	6%	4%	5%	5%
Work limitation	Not limited	86%	2%	38%	5%	9%
	Limited	14%	98%	62%	95%	91%
Personal care limitation	Does not need help	98%	42%	77%	33%	35%
	Needs help	2%	58%	23%	67%	65%
Usual activity limitation	Not limited	90%	1%	34%	0%	7%
	Limited	10%	99%	66%	100%	93%
Difficulty carrying	None	88%	3%	35%	5%	9%
	Minor	7%	39%	47%	51%	40%
	Major	6%	58%	18%	44%	51%
Difficulty kneeling	None	74%	3%	22%	2%	2%
	Minor	15%	23%	50%	28%	35%
	Major	10%	73%	28%	70%	63%
Difficulty sitting	None	87%	0%	18%	0%	2%
	Minor	11%	3%	23%	16%	16%
	Major	2%	97%	58%	84%	81%
Difficulty climbing stairs	None	86%	5%	47%	14%	19%
	Minor	8%	53%	37%	53%	40%
	Major	6%	42%	15%	33%	42%
Difficulty standing	None	78%	1%	19%	0%	7%
	Minor	15%	7%	24%	9%	7%
	Major	7%	92%	57%	91%	86%
Difficulty walking	None	81%	7%	48%	14%	14%
	Minor	10%	39%	31%	33%	23%
	Major	9%	54%	20%	53%	63%

Abbreviations: NHIS, National Health Interview Survey; SIJ, sacroiliac joint; NSM, nonsurgical management; yrs, years.

Table 2 Predicted probability of working, earnings, and productivity by treatment group and period

Category	Treatment	Period	Mean	Lower 95% CI	Upper 95% CI
Predicted probability of working	NSM	Baseline	19%	14%	24%
		6 months	22%	16%	28%
		Change	3%	−3%	9%
	SIJ fusion	Baseline	19%	17%	21%
		6 months	38%	35%	41%
		Change	19%	15%	22%
Predicted earnings of workers	NSM	Baseline	$30,926	$23,012	$38,734
		6 months	$31,481	$23,132	$40,041
		Change	$555	–$10,806	$11,440
	SIJ fusion	Baseline	$29,836	$26,779	$32,969
		6 months	$33,519	$30,469	$36,661
		Change	$3,683	–$446	$7,889
Mean aggregate productivity	NSM	Baseline	$7,075	$4,099	$10,481
		6 months	$8,358	$4,843	$12,105
		Change	$1,283	–$3,191	$5,852
	SIJ fusion	Baseline	$6,669	$5,552	$7,792
		6 months	$14,875	$12,744	$17,049
		Change	$8,206	$5,999	$10,304

Notes: Mean aggregate productivity = expected earnings = probability of working × earnings. All values are in US dollars.

Abbreviations: SIJ, sacroiliac joint; NSM, nonsurgical management; CI, confidence interval.

Table 3 Change in annual economic outcomes for patients treated with SIJ fusion compared to NSM

Category	Mean	Lower 95% CI	Upper 95% CI
Expected change in probability of working	0.16	0.09	0.22
Expected change in earnings	$3,128	–$9,036	$14,958
Expected change in aggregate productivity	$6,924	$1,890	$11,945

Note: Mean aggregate productivity = probability of working × earnings conditional on working. All values are in US dollars.

Abbreviations: SIJ, sacroiliac joint; NSM, nonsurgical management; CI, confidence interval.

Figure 1 Prediction percentiles for the aggregate productivity change for a given patient.

Note: Aggregate productivity = probability of working × earnings.
Abbreviations: NSM, nonsurgical management; SIJ, sacroiliac joint.