Unit costs
Cost of intervention: The intervention is a single dose
of IV co-amoxiclav, given post-delivery. Since co-amoxiclav is already
widely used within the NHS, its cost could be reliably estimated from
the British National Formulary (BNF). The ANODE trial reports an average
NHS indicative cost for the 3 main providers of co-amoxiclav powder
calculated using the BNF 20178, totalling £2.30. For
this economic evaluation, the same methodology was employed but with
updated costs from the BNF 202013, yielding an average
price of £2.26. A placebo of 0.9% saline was the comparator and just as
in the ANODE trial this was attributed no cost.
Cost of complications: In order for the cost of
complications to be accurate, the typical patient journey and the
likelihood of using certain NHS resources over that journey needed to be
considered. This was informed by an NHS flowchart obtained from the
Royal Berkshire Hospital NHS Foundation Trust guidelines on postpartum
infection (Appendix S3). This highlighted the role of home visits by
midwives as the first healthcare point of contact for mothers with
suspected postpartum complications and this was consequently included in
all cost estimates. Literature searches on standard treatments for each
specific complication informed the cost at each terminal node. In
certain cases, assumptions were made to estimate the costs of specific
complications. A cost for systemic infection but without subsequent
development of sepsis was not obtainable; therefore, the treatment cost
associated with sepsis was utilised for all outcomes of systemic
infection. This is justified as irrespective of the development of
sepsis, systemic infections will necessitate similar treatment costs, as
reflected in the National Tariff17. Other assumptions
included that patients were only re-admitted into hospital for systemic
infection, endometritis and wound breakdown and that all patients with
“other or confirmed suspected infections” were treated in the
community.
Discounting : To ensure all costs were accurate, sources
of cost data used were UK-based and from the year of the trial (March
2016-) or newer. Moreover, all but one of the costs were taken directly
from NHS reference costs, the British National Formulary (BNF) or
government reports. Historical costs were discounted at a rate of 3.5%
in line with NICE guidelines18, converting all costs
into the year 2020.