How to pronounce ±?

Read it as "add and subtract?"

Context:

Results
Of the 66 randomly assigned patients, the 33 in the tai chi group had clinically important improvements in the FIQ total score and quality of life. Mean (±SD) baseline and 12-week FIQ scores for the tai chi group were 62.9±15.5 and 35.1±18.8, respectively, versus 68.0±11 and 58.6±17.6, respectively, for the control group (change from baseline in the tai chi group vs. change from baseline in the control group, −18.4 points; P<0.001). The corresponding SF-36 physical-component scores were 28.5±8.4 and 37.0±10.5 for the tai chi group versus 28.0±7.8 and 29.4±7.4 for the control group (between-group difference, 7.1 points; P=0.001), and the mental-component scores were 42.6±12.2 and 50.3±10.2 for the tai chi group versus 37.8±10.5 and 39.4±11.9 for the control group (between-group difference, 6.1 points; P=0.03). Improvements were maintained at 24 weeks (between-group difference in the FIQ score, −18.3 points; P<0.001). No adverse events were observed.