Porphyria attacks were defined as meeting all of the following criteria: an acute episode of neurovisceral pain in the abdomen, back, chest, extremities and/or limbs, no other medically determined cause, and required treatment with intravenous (IV) dextrose or hemin, carbohydrates, or analgesics, or other medications such as antiemetics at a dose or frequency beyond the participant's usual daily porphyria management. The annualized rate of porphyria attacks is a composite endpoint which included porphyria attacks requiring hospitalization, urgent healthcare visit, or IV hemin administration at home.

AIP participants in the Full Analysis Set (FASAIP): All randomized AIP participants (with identified mutation in the hydroxymethylbilane synthase [HMBS] gene) who received at least one dose of study drug.

The PD effect of givosiran was evaluated by spot urine ALA levels normalized to spot urine creatinine levels.

FASAIP: All randomized AIP participants (with identified mutation in the HMBS gene) who received at least one dose of study drug.

The PD effect of givosiran was evaluated by spot urine PBG levels normalized to spot urine creatinine levels.

FASAIP: All randomized AIP participants (with identified mutation in the HMBS gene) who received at least one dose of study drug.

Annualized rate of hemin doses was evaluated as annualized days of hemin use.

FASAIP: All randomized AIP participants (with identified mutation in the HMBS gene) who received at least one dose of study drug.

Porphyria attacks were defined as meeting all of the following criteria: an acute episode of neurovisceral pain in the abdomen, back, chest, extremities and/or limbs, no other medically determined cause, and required treatment with intravenous (IV) dextrose or hemin, carbohydrates, or analgesics, or other medications such as antiemetics at a dose or frequency beyond the participant's usual daily porphyria management. The annualized rate of porphyria attacks is a composite endpoint which included porphyria attacks requiring hospitalization, urgent healthcare visit, or IV hemin administration at home.

Full Analysis Set (FAS): All randomized patients who received at least one dose of study drug.

Participants rated worst daily pain score in an eDiary using the 11-point BPI-SF NRS, in which 0=no pain and 10=worst pain. Daily eDiary entries were averaged into a weekly (i.e. 7 day) score. The change from baseline in weekly mean scores is defined as the post baseline weekly mean score minus the baseline score. Lower scores indicate an improvement. The 6-month AUC was calculated based on change from baseline in weekly mean scores.

FASAIP: All randomized AIP participants (with identified mutation in the HMBS gene) who received at least one dose of study drug.

Participants rated worst daily pain score in an eDiary using the 11-point BPI-SF NRS, in which 0=no pain and 10=worst pain. Daily eDiary entries were averaged into a weekly (i.e. 7 day) score. The change from baseline in weekly mean scores is defined as the postbaseline weekly mean score minus the baseline score. Lower scores indicate an improvement.

FASAIP: All randomized AIP participants (with identified mutation in the HMBS gene) who received at least one dose of study drug.

Participants rated daily worst fatigue score in an eDiary using the 11-point BFI-SF NRS, in which 0=no fatigue and 10=worst fatigue. Daily eDiary entries were averaged into a weekly (i.e. 7 day) score. The change from baseline in weekly mean scores is defined as the post baseline weekly mean score minus the baseline score. Lower scores indicate an improvement. The 6-month AUC was calculated based on change from baseline in weekly mean scores.

FASAIP: All randomized AIP participants (with identified mutation in the HMBS gene) who received at least one dose of study drug.

Participants rated daily worst fatigue score in an eDiary using the 11-point BFI-SF NRS, in which 0=no fatigue and 10=worst fatigue. Daily eDiary entries were averaged into a weekly (i.e. 7 day) score. The change from baseline in weekly mean scores is defined as the postbaseline weekly mean score minus the baseline score. Lower scores indicate an improvement.

FASAIP: All randomized AIP participants (with identified mutation in the HMBS gene) who received at least one dose of study drug.

Participants rated worst daily nausea score in an eDiary using an 11-point NRS, in which 0=no nausea and 10=worst nausea. Daily eDiary entries were averaged into a weekly (i.e. 7 day) score. The change from baseline in weekly mean scores is defined as the postbaseline weekly mean score minus the baseline score. Lower scores indicate an improvement. The 6-month AUC was calculated based on change from baseline in weekly mean scores.

FASAIP: All randomized AIP participants (with identified mutation in the HMBS gene) who received at least one dose of study drug.

Participants rated worst daily nausea score in an eDiary using an 11-point NRS, in which 0=no nausea and 10=worst nausea. Daily eDiary entries were averaged into a weekly (i.e. 7 day) score. The change from baseline in weekly mean scores is defined as the postbaseline weekly mean score minus the baseline score. Lower scores indicate an improvement.

FASAIP: All randomized AIP participants (with identified mutation in the HMBS gene) who received at least one dose of study drug.

The SF-12 is a survey designed for use in patients with multiple chronic conditions. This 12-item scale can be used to assess the physical and mental health of respondents. 10 of the 12 questions are answered on a 5 point likert scale and 2 are answered on a 3 point likert scale. The questions are then scored and weighted into 2 subscales, physical health and mental health. Respondents can have a score that ranges from 0-100 with 100 being the best score and indicating high physical or mental health. A 3 point change in SF-12 score reflects a meaningful difference. A higher score indicates improvement.

FASAIP: All randomized AIP participants (with identified mutation in the HMBS gene) who received at least one dose of study drug.