9 14 Health service factors included the number of antenatal clinic visits, categorised as no antenatal visit, one to three antenatal visit or four and above antenatal visits, which reflects the WHO four-visit antenatal care (ANC) model for focused ANC, 20 the place of delivery (home or health facility) and the timing of postnatal visits (categorised as none, 0 2 days or 3 42 days).
The number of ANC visits was categorised into one-three visits and four or more ANC visits.
The NSW ED surveillance system was originally established for syndromic surveillance and uses groupings of ED diagnoses to categorise ED visits into syndromes.
We categorised primary care visits into three equally sized categories of low, medium or high utilisation based on observed frequencies (ie, 0 2, 3 9 or ≥10 visits).
The Ordnance Survey MasterMap Integrated Transportation Network dataset [ 49] provides detailed road and footpath information and the Ordnance Survey Points of Interest database contains places that can be visited, categorised by types, such as pubs, clubs or restaurants [ 50].
In a recent American study, when ED visits categorised as 'primary-care treatable' at discharge were assessed with information on main complaint presented at admission, only 6% remained as 'primary care treatable'.
Visual acuity was tested at each visit and categorised as ≥6/9, <6/9 but >6/120, or ≥6/120, with improvement in visual acuity defined by an improvement in class.
Self-reported alcohol consumption at the booking visit was categorised as low (0-5 units per week), moderate (6-20 units per week) and high (>20 units per week).
For each visit we categorised couples according to antiretroviral therapy of the index partner: not taking antiretroviral treatment, taking monotherapy/dual therapy, and taking combined therapy with at least three active drugs.
We calculated body mass index from weight and height at the first antenatal visit and categorised the women as underweight (body mass index <18.5), of normal weight (18.5-24.9), overweight (25.0-29.9), obesityity class 1 (30.0-34.9), 2 (35.0-39.9), or 3 (≥40.0).
Smoking status at first antenatal care visit was categorised and assessed as follows: 1) Non-smoker, 2) smoke one to nine cigarettes per day, and 3) smoke ten or more cigarettes per day.
