TABLE IV.

Mean Differences in the Orthogonal, Oblique, and RAND-36 HSI Summary Scores Between Baseline or Preoperative and Follow-up SF-36 Results^*

	Oblique – Orthogonal		RAND-36 – Orthogonal
	Mean ΔPCS	Mean ΔMCS	Mean ΔPCS	Mean ΔMCS
Baseline or preop. results	2.77	−5.34	1.57	−5.91
Follow-up results	2.48	−2.50	1.41	−2.05
Difference (95% CI)†	0.29 (−0.61, 1.19)	−2.84 (−3.77, −1.90)	0.16 (−0.55, 0.88)	−3.86 (−4.84, −2.89)

^*Mean differences in the orthogonal, oblique, and RAND-36 HSI summary scores between baseline or preop. and follow-up SF-36 results. The studies tabulated in Table III were averaged to demonstrate that the oblique scoring method increased the PCS by 2.77 points for preop./baseline values or 2.48 points for follow-up values. The minimal clinically important difference for the SF-36 is 3 points²⁷.

^†Paired-sample t test. CI = confidence interval.