All patients received a conditioning dose of placebo equivalent SC on Day 0, followed by 11 weekly doses of placebo SC beginning on Day 7. After 12 weeks of blinded treatment, all patients continued into the open-label efalizumab treatment period from Day 84 (Week 12) through Day 168 (Week 24).

Proportion of patients who achieved a ≥ 50% decrease in PSSI score at 12 weeks (Day 84) relative to baseline. The PSSI assessed: 1) extent of scalp psoriasis (i.e., percentage of area involved), which was scored from 1 to 6, where 1 = <10% and 6 = 90-100%); and 2) clinical signs (erythema, induration, and desquamation), which were scored from 0 to 4, where 0 = Absent and 4 = Severest possible). The sum of the separate scores for erythema, induration, and desquamation was multiplied by the score for the involved area. The PSSI score range was therefore 0-72.

Proportion of patients who achieved a ≥ 50% decrease in PSSI score at 24 weeks (Day 168) relative to baseline. The PSSI assessed: 1) extent of scalp psoriasis (i.e., percentage of area involved), which was scored from 1 to 6, where 1 = <10% and 6 = 90-100%); and 2) clinical signs (erythema, induration, and desquamation), which were scored from 0 to 4, where 0 = Absent and 4 = Severest possible). The sum of the separate scores for erythema, induration, and desquamation was multiplied by the score for the involved area. The PSSI score range was therefore 0-72.

Proportion of patients who achieved a whole body (including scalp) PGA rating of 0, 1, or 2 at 12 weeks (Day 84)

Physician's Global Assessment (PGA) scale:

0: Clear. No signs of plaque psoriasis.

1. Almost clear. Just perceptible erythema and just perceptible scaling.
2. Mild disease. Light pink erythema with minimal scaling.
3. Moderate disease. Dull red, clearly distinguishable erythema with diffuse scaling, some thickening.
4. Severe disease. Deep/dark red erythema with clearly obvious and diffuse scaling and thickening.

Proportion of patients who achieved a whole body (including scalp) PGA rating of 0, 1, or 2 at 24 weeks (Day 168) For details on the PGA scale, refer to the Secondary Outcome Measure Description for 12 weeks.

Mean change in Scalpdex score at 12 weeks (Day 84) relative to baseline. The Scalpdex point scoring scale ranges from 1=NEVER, 2='RARELY', 3='SOMETIMES', 4='OFTEN' and 5='ALL THE TIME'.

Mean change in Scalpdex score at 24 weeks (Day 168) relative to baseline. The Scalpdex point scoring scale ranges from 1=NEVER, 2='RARELY', 3='SOMETIMES', 4='OFTEN' and 5='ALL THE TIME'.

Mean change in VAS of patient-reported scalp itch at 12 weeks (Day 84) relative to baseline. The Visual Analog Scale (VAS) of patient-reported scalp itch measured the severity of a patient's scalp itch on a scale of 0 to 10, where 0 was "no itching," 5 was "moderate itching," and 10 was "severe itching."

Mean change in VAS of patient-reported scalp itch at 24 weeks (Day 168) relative to baseline. The Visual Analog Scale (VAS) of patient-reported scalp itch measured the severity of a patient's scalp itch on a scale of 0 to 10, where 0 was "no itching," 5 was "moderate itching," and 10 was "severe itching."

Mean change in percentage of whole body (including scalp) BSA affected by psoriasis at 12 weeks (Day 84) relative to baseline. BSA was assessed by percentage of sites affected per body segment (head, trunk, and limbs). Investigators were instructed to use the "rule of palm" to estimate lesional skin BSA (1% BSA = palm to first interphalangeal joint).

Mean change in percentage of whole body (including scalp) BSA affected by psoriasis at 24 weeks (Day 168) relative to baseline. BSA was assessed by percentage of sites affected per body segment (head, trunk, and limbs). Investigators were instructed to use the "rule of palm" to estimate lesional skin BSA (1% BSA = palm to first interphalangeal joint).

Total of all reporting groups

All patients received a conditioning dose of efalizumab 0.7 mg/kg subcutaneously (SC) on Day 0, followed by 11 weekly doses of 1.0 mg/kg SC beginning on Day 7. After 12 weeks of blinded treatment, all patients continued into the open-label treatment period from Day 84 (Week 12) through Day 168 (Week 24).

Proportion of patients who achieved a ≥ 75% decrease in PSSI score at 24 weeks (Day 168) relative to baseline. The PSSI assessed: 1) extent of scalp psoriasis (i.e., percentage of area involved), which was scored from 1 to 6, where 1 = <10% and 6 = 90-100%); and 2) clinical signs (erythema, induration, and desquamation), which were scored from 0 to 4, where 0 = Absent and 4 = Severest possible). The sum of the separate scores for erythema, induration, and desquamation was multiplied by the score for the involved area. The PSSI score range was therefore 0-72.

ITT population. If PSSI at Day 168 was missing for a patient who discontinued before the final scheduled open-label dose, the patient was considered a treatment failure (nonresponder) for analysis. If PSSI at Day 168 was missing for a patient who completed the Day 161 dose, the last available PSSI was used for analysis.

Proportion of patients who achieved a ≥ 50% decrease in PSSI score at 12 weeks (Day 84) relative to baseline. The PSSI assessed: 1) extent of scalp psoriasis (i.e., percentage of area involved), which was scored from 1 to 6, where 1 = <10% and 6 = 90-100%); and 2) clinical signs (erythema, induration, and desquamation), which were scored from 0 to 4, where 0 = Absent and 4 = Severest possible). The sum of the separate scores for erythema, induration, and desquamation was multiplied by the score for the involved area. The PSSI score range was therefore 0-72.

ITT population. If PSSI at Day 84 was missing for a patient who discontinued before the final scheduled dose, the patient was considered a treatment failure (nonresponder) for analysis. If PSSI at Day 84 was missing for a patient who completed treatment, the last available PSSI from the treatment period was used for analysis.

Proportion of patients who achieved a ≥ 50% decrease in PSSI score at 24 weeks (Day 168) relative to baseline. The PSSI assessed: 1) extent of scalp psoriasis (i.e., percentage of area involved), which was scored from 1 to 6, where 1 = <10% and 6 = 90-100%); and 2) clinical signs (erythema, induration, and desquamation), which were scored from 0 to 4, where 0 = Absent and 4 = Severest possible). The sum of the separate scores for erythema, induration, and desquamation was multiplied by the score for the involved area. The PSSI score range was therefore 0-72.

ITT population. If PSSI at Day 168 was missing for a patient who discontinued before the final scheduled open-label dose, the patient was considered a treatment failure (nonresponder) for analysis. If PSSI at Day 168 was missing for a patient who completed the Day 161 dose, the last available PSSI was used for analysis.

Proportion of patients who achieved a whole body (including scalp) PGA rating of 0, 1, or 2 at 12 weeks (Day 84)

Physician's Global Assessment (PGA) scale:

0: Clear. No signs of plaque psoriasis.

1. Almost clear. Just perceptible erythema and just perceptible scaling.
2. Mild disease. Light pink erythema with minimal scaling.
3. Moderate disease. Dull red, clearly distinguishable erythema with diffuse scaling, some thickening.
4. Severe disease. Deep/dark red erythema with clearly obvious and diffuse scaling and thickening.

ITT population. If PGA rating at Day 84 was missing for a patient who discontinued before the final scheduled dose, the patient was considered a treatment failure (nonresponder) for analysis. If PGA rating at Day 84 was missing for a patient who completed treatment, the last available PGA rating from the treatment period was used for analysis.

Proportion of patients who achieved a whole body (including scalp) PGA rating of 0, 1, or 2 at 24 weeks (Day 168) For details on the PGA scale, refer to the Secondary Outcome Measure Description for 12 weeks.

ITT population. If PGA rating at Day 168 was missing for a patient who discontinued before the final scheduled open-label dose, the patient was considered a treatment failure (nonresponder) for analysis. If PGA rating at Day 168 was missing for a patient who completed the Day 161 dose, the last available PGA rating was used for analysis.

Mean change in Scalpdex score at 12 weeks (Day 84) relative to baseline. The Scalpdex point scoring scale ranges from 1=NEVER, 2='RARELY', 3='SOMETIMES', 4='OFTEN' and 5='ALL THE TIME'.

ITT population. If Scalpdex at Day 84 was missing for a patient who discontinued before the final scheduled dose, the patient was not included in the analysis. If Scalpdex at Day 84 was missing for a patient who completed treatment, the last available Scalpdex from the treatment period was used for analysis.

Mean change in Scalpdex score at 24 weeks (Day 168) relative to baseline. The Scalpdex point scoring scale ranges from 1=NEVER, 2='RARELY', 3='SOMETIMES', 4='OFTEN' and 5='ALL THE TIME'.

ITT population. If Scalpdex at Day 168 was missing for a patient who discontinued before the final scheduled dose, the patient was not included in the analysis. If Scalpdex at Day 168 was missing for a patient who completed the Day 161 dose, the last available Scalpdex was used for analysis.

Mean change in VAS of patient-reported scalp itch at 12 weeks (Day 84) relative to baseline. The Visual Analog Scale (VAS) of patient-reported scalp itch measured the severity of a patient's scalp itch on a scale of 0 to 10, where 0 was "no itching," 5 was "moderate itching," and 10 was "severe itching."

ITT population. If VAS at Day 84 was missing for a patient who discontinued before the final scheduled dose, the patient was not included in the analysis. If VAS at Day 84 was missing for a patient who completed treatment, the last available VAS from the treatment period was used for analysis.

Mean change in VAS of patient-reported scalp itch at 24 weeks (Day 168) relative to baseline. The Visual Analog Scale (VAS) of patient-reported scalp itch measured the severity of a patient's scalp itch on a scale of 0 to 10, where 0 was "no itching," 5 was "moderate itching," and 10 was "severe itching."

ITT population. If VAS at Day 168 was missing for a patient who discontinued before the final scheduled dose, the patient was not included in the analysis. If VAS at Day 168 was missing for a patient who completed the Day 161 dose, the last available VAS was used for analysis.

Mean change in percentage of whole body (including scalp) BSA affected by psoriasis at 12 weeks (Day 84) relative to baseline. BSA was assessed by percentage of sites affected per body segment (head, trunk, and limbs). Investigators were instructed to use the "rule of palm" to estimate lesional skin BSA (1% BSA = palm to first interphalangeal joint).

ITT population. N's reflect patients who received at least one dose of study drug or placebo in the double-blind treatment period.

Mean change in percentage of whole body (including scalp) BSA affected by psoriasis at 24 weeks (Day 168) relative to baseline. BSA was assessed by percentage of sites affected per body segment (head, trunk, and limbs). Investigators were instructed to use the "rule of palm" to estimate lesional skin BSA (1% BSA = palm to first interphalangeal joint).

ITT population. N's reflect patients who received at least one dose of study drug in the open-label period.

All patients received a conditioning dose of efalizumab 0.7 mg/kg subcutaneously (SC) on Day 0, followed by 11 weekly doses of 1.0 mg/kg SC beginning on Day 7. After 12 weeks of blinded treatment, all patients continued into the open-label treatment period from Day 84 (Week 12) through Day 168 (Week 24).