Table 2 Change from baseline in the behavioral outcome measures for the 4-week arginine vasopressin (AVP) treatment trial.

Data were analyzed using the same model throughout (which controlled for ethnicity, IQ, pretreatment blood differential receptor gene expression, and baseline behavioral severity for each measure). All analyses tested for a main effect of treatment condition at the mean pretreatment blood AVP concentration. This LSM response takes into account any predictive effect of pretreatment blood AVP concentration on treatment response and gives an overall measure of efficacy in the population of participants as a whole. The ability of pretreatment blood AVP concentration to predict treatment response differentially in the drug-treated group is tested by the treatment condition–by–pretreatment blood AVP concentration interaction. Clinical Global Impression-Improvement (CGI-I) is a single score taken after a 4-week treatment. Otherwise, all other scores are given as a change from baseline, normalized for the direction of the scale, so that symptomatic improvement is reported as a positive change. For all measures, significant overall effects of treatment condition are in the predicted direction (i.e., AVP-treated participants improve more than placebo-treated participants). When a treatment condition–by–pretreatment blood AVP concentration interaction is significant, post hoc tests are reported for AVP-treated and placebo-treated participants: “Greater” indicates that symptomatic improvement increased with higher pretreatment blood concentrations of AVP; “Lesser” indicates that less improvement was observed at higher pretreatment blood concentrations of AVP; “ns” indicates that the scale was not significantly affected by pretreatment blood AVP concentrations. Subscales of an instrument are only tested if the overall score is significant at P < 0.05 and are tested at appropriate Bonferroni-corrected critical α to minimize the risk of false discovery. (Social Behavior Scale, 2nd Edition (SRS-2), critical α < 0.025; Repetitive Behaviors Scale-Revised (RBS-R), critical α < 0.0083). Any post hoc tests of treatment condition–by–pretreatment blood AVP concentration interactions are further Bonferroni-corrected to a critical α half that of the original critical α for the interaction. Effect sizes are given as ηp2. SCI, Social Communication and Interaction; RRB, Restricted Interests and Repetitive Behavior; CGI-S, Clinical Global Impression-Severity; FERT, Facial Emotion Recognition Test; RMET, Reading the Mind in the Eyes Test; NEPSY, Developmental NEuroPSYchological Assessment.

MeasureTreatment condition
main effect
Improvement in
score LSM ± SE
*Significant
after
correction
for multiple
comparisons
Treatment condition–
by–pretreatment blood
AVP concentration
interaction
*Significant
after
correction
for multiple
comparisons
Improvement in score
becomes greater or
lesser with higher
pretreatment blood
AVP concentrations
AVPPlaceboAVPPlacebo
Primary outcome measure
SRS-2 T scoreF1,20 = 9.853; P = 0.0052;
ηp2 = 33.0%
17.6 ± 1.3710.8 ± 2.11*F1,20 = 50.49; P < 0.0001;
ηp2 = 71.6%
*GreaterLesser
  SCIF1,20 = 12.74; P = 0.0019;
ηp2 = 38.9%
17.5 ± 1.379.75 ± 2.11*F1,20 = 58.38; P < 0.0001;
ηp2 = 74.5%
*GreaterLesser
  RRBF1,20 = 1.045; P = 0.3188;
ηp2 = 5.0%
15.6 ± 1.7312.7 ± 2.70nsF1,20 = 7.601; P = 0.0122;
ηp2 = 27.5%
*Greaterns
Secondary outcome measures (clinician-evaluated)
CGI-S, social and
communication
F1,20 = 0.549; P = 0.4674;
ηp2 = 2.7%
0.873 ± 0.1260.712 ± 0.202nsF1,20 = 1.519; P = 0.2320;
ηp2 = 7.1%
ns
CGI-I, social and
communication
F1,21 = 7.098; P = 0.0145;
ηp2 = 25.3%
2.23 ± 0.1492.93 ± 0.244*F1,21 = 9.520; P = 0.0056;
ηp2 = 31.2%
*Greaterns
Secondary outcome measures (parent-rated)
Spence Children’s
Anxiety Scale
F1,20 = 9.014; P = 0.0070;
ηp2 = 31.1%
17.9 ± 1.669.14 ± 2.68*F1,20 = 19.48; P = 0.0003;
ηp2 = 49.3%
*GreaterLesser
RBS-R—totalF1,19 = 1.600; P = 0.2213;
ηp2 = 7.8%
17.2 ± 1.8321.3 ± 3.18nsF1,19 = 18.57; P = 0.0004;
ηp2 = 49.4%
*Greaterns
  StereotypicF1,19 = 0.001; P = 0.9783;
ηp2 = 0.0%
2.24 ± 0.3132.23 ± 0.486nsF1,19 = 4.932; P = 0.0381;
ηp2 = 20.6%
ns
  Self-injuriousF1,19 = 0.552; P = 0.4666;
ηp2 = 2.8%
0.594 ± 0.4671.18 ± 0.828nsF1,19 = 27.54; P < 0.0001;
ηp2 = 59.2%
*GreaterLesser
  CompulsiveF1,19 = 2.028; P = 0.1707;
ηp2 = 9.6%
3.35 ± 0.5114.59 ± 0.819nsF1,19 = 22.49 ; P = 0.0001;
ηp2 = 54.2%
*Greaterns
  RitualisticF1,19 = 3.133; P = 0.0920;
ηp2 = 14.2%
3.08 ± 0.5044.63 ± 0.818nsF1,19 = 3.643; P = 0.0708;
ηp2 = 16.1%
ns
  SamenessF1,19 = 0.043; P = 0.8375;
ηp2 = 0.2%
5.61 ± 0.6615.85 ± 1.03nsF1,19 = 3.071; P = 0.0950;
ηp2 = 13.9%
ns
  RestrictedF1,19 = 0.623; P = 0.4392;
ηp2 = 3.2%
2.58 ± 0.543.4 ± 1.01nsF1,19 = 4.261; P = 0.0522;
ηp2 = 18.3%
ns
Secondary outcome measures (child performance)
FERTF1,7 = 10.85; P = 0.0132;
ηp2 = 60.8%
3.10 ± 2.42−7.19 ± 1.81*F1,7 = 0.971; P = 0.3573;
ηp2 = 12.2%
ns
RMETF1,6 = 6.2341; P = 0.0467;
ηp2 = 51.0%
4.04 ± 1.63−1.28 ± 1.24*F1,6 = 0.068; P = 0.8031;
ηp2 = 1.1%
ns
NEPSY—Theory of
Mind
F1,12 = 0.647; P =0.4367;
ηp2= 5.1%
2.1 ± 1.410.677 ± 1.20nsF1,12 = 1.162; P =0.3022;
ηp2= 8.8%
ns
NEPSY—Affect
Recognition
F1,12 = 0.946; P = 0.3500;
ηp2 = 7.3%
0.094 ± 2.20−2.58 ± 1.90nsF1,12 = 0.251; P = 0.6254;
ηp2 = 2.0%
ns