Draft monograph: tirzepatide, version 2 — submissions
The 15 submissions received, published in full with declared interests and secretariat responses.
§2Submissions and responses
15 submissions were received. Each is published in full below with its declared interest, the secretariat response and the disposition. The Institute publishes submissions it did not accept in the same form as those it did.
Local reactions are omitted from the adverse-event table because the trials reported them separately
This is a submission on the draft covering Tirzepatide, from a respondent whose work is with the people taking compounds of this class rather than with the trials that produced them.
Injection-site reactions are reported in the source trials in a table of their own and do not appear in the systemic adverse-event table the monograph reproduces. The result is that the most common adverse experience of a subcutaneously administered compound is absent from the monograph’s adverse-event section.
The respondent proposes that local reactions be carried in the same table as systemic events, with the reporting convention of the source trial recorded in a footnote.
The secretariat accepts this submission. The omission arose from following the source tables and it produced a misleading total.
Local reactions are now carried in the adverse-event table wherever the source trials report them, footnoted with the convention each trial used.
Effect estimates are given without naming the comparator
The respondent has read Tirzepatide and submits on a matter of presentation.
Several estimates in the draft state an effect without stating what it was measured against. An estimate against placebo and an estimate against an active comparator are not the same quantity and the draft presents them in one column.
The respondent proposes that the comparator be part of every outcome row rather than a footnote, and that estimates against different comparators never share a column.
The respondent endorses the general approach taken in submission 001 and asks that it be extended to the matter identified here.
The secretariat accepts this submission. A footnoted comparator is a comparator a reader will not carry into the next row.
The comparator is now stated in every outcome row, and estimates against different comparators are reported in separate tables with the comparator named in the table caption.
The analytical section assumes a reference standard that is not generally available
The draft on Tirzepatide was read in full. The respondent notes at the outset that this class has an unusually deep randomised evidence base, and that a monograph on it is fairly judged against a higher standard than one on a compound with none.
The draft describes identity and content determinations that require a reference standard of assigned content. For this compound no such standard is in general circulation, and a laboratory following the section as written cannot perform the determination described.
The respondent, employed by a contract analytical laboratory, proposes that the monograph state explicitly where a reference standard is unavailable and what a determination performed without one can still establish.
The secretariat accepts this submission. The section described an ideal case and did not say so.
The analytical section now states whether a reference standard is in general circulation for this compound and, where it is not, states which determinations remain possible and which become qualitative. A content figure obtained without a reference standard is recorded as an estimate against a stated assumption rather than as a determination.
Guidance on lyophilised storage is missing
This submission concerns Tirzepatide and a convention used across the Institute’s output.
The respondent asks that the monograph state storage conditions for lyophilised material as well as for reconstituted solution, since the two differ and the former governs the longer part of the shelf life.
The respondent states that the omission is the more consequential because lyophilised material is what is generally received.
The secretariat notes this submission. The draft addresses lyophilised storage, in the presentation section rather than in the section on in-use handling, which is where the respondent looked.
No amendment to content arises. The two storage statements have been brought together under a single heading so that a reader looking for either finds both.
The recorded evidence gaps omit outcomes a reader would consider material
The respondent works on cardiometabolic outcomes and read the draft on Tirzepatide with that literature in view.
The evidence-gap section records what has not been studied. The respondent, a practising clinician, states that the list is drawn from the outcomes the trials chose to measure and therefore reproduces the sponsor's outcome selection rather than correcting for it.
The respondent proposes that the gap list be constructed from the outcomes a prescribing decision turns on, and that outcomes measured by no trial appear in it as such.
The secretariat accepts this submission in part. The gap list is reconstructed from the decision-relevant outcome set rather than from the measured set. The proposal that every unmeasured outcome be listed is declined, because an unbounded list of things not studied is not a finding.
The evidence-gap section is now derived from the anchor and decision-relevant outcomes for the indication, and any such outcome measured by no contributing trial is recorded as not measured rather than omitted.
Where the compound is a glucagon-like peptide-1 receptor agonist, the cardiovascular outcome evidence should be an assessed outcome
The respondent submits on the draft monograph for Tirzepatide. The observation arises from teaching the material rather than from prescribing it.
The respondent states that for compounds in this class the cardiovascular outcome evidence, reported for semaglutide in SELECT in the New England Journal of Medicine in 2023 and for liraglutide in LEADER in the same journal in 2016, is the evidence a prescribing decision most often turns on, and that the draft treats it as background.
The respondent proposes that cardiovascular outcomes be an assessed outcome with its own certainty rating for every compound in the class for which such a trial exists.
The respondent has read submission 003 with interest and adds one observation the secretariat may find useful.
The secretariat accepts this submission in part. Cardiovascular outcomes become an assessed outcome where a dedicated outcome trial of the compound exists. The proposal to extend the rating across the class by inference is declined, in line with the treatment of class-level extrapolation elsewhere in the series.
Cardiovascular outcomes are now an assessed outcome with their own certainty rating in every monograph for which a dedicated cardiovascular outcome trial of that compound has reported, and are recorded as not assessed elsewhere.
The same concept is given three different names in one document
The respondent read the draft on Tirzepatide alongside the approved labelling for the class, and submits on one matter arising.
The draft refers to the same quantity as a response rate, a responder proportion and a categorical outcome in different sections. The respondent, who works in health-technology assessment, states that a reader cannot tell whether the three refer to one thing or to three.
The respondent proposes that the glossary term be used at every occurrence and that the glossary entry be linked at first use in each section rather than only at first use in the document.
The secretariat accepts this submission. The variation was stylistic and its cost to the reader exceeds any benefit.
A single term is now used throughout for each defined concept, and the glossary entry is linked at first use within each section rather than once per document.
The document is unreadable without specialist training
Having reviewed the draft on Tirzepatide, the respondent makes a single submission, on the view that one point put clearly is more use to the secretariat than six put together.
The respondent states that the draft is written for a reader who already understands certainty grading, and that the people most affected by the subject matter will not reach the assessment at all.
The respondent proposes a plain-language summary at the head of every document, written to the same standard of accuracy as the document itself and not as a promotional abstract.
The secretariat accepts this submission in part. A plain-language summary is added. The proposal that it replace the technical abstract is declined, because the abstract is the part of the document other assessors read and cite.
Every document now opens with a plain-language summary of not more than 150 words, placed above the technical abstract and carrying the same certainty language, so that the two cannot diverge.
Registered trials that never reported are absent from the monograph
The respondent submits on Tirzepatide.
The respondent states that the trial list appears to be drawn from published reports, and that registered trials which completed without a report are therefore invisible. The proportion of a programme that never reported is itself a finding about the evidence base.
The respondent proposes that every registered trial of the compound be listed, with its reporting status, whether or not a report exists.
The secretariat accepts this submission. A trial list built from publications reproduces publication bias in the shape of the document.
The trial list now includes every registered trial the Institute identified, with its reporting status stated, and the monograph reports the proportion of registered trials for which no result has been posted or published.
What happens to weight after the compound is stopped is not in the assessed outcomes
This submission addresses the draft monograph on Tirzepatide. The respondent went through the document twice, once as a specialist and once as a reader arriving without the background.
Several trials in the evidence base ran a withdrawal period and reported what happened. That evidence is the single most useful thing a person considering the compound could be told, and it appears in the monograph only as a sentence in the discussion.
The respondent proposes that post-withdrawal trajectory be an assessed outcome in its own right for every compound where a withdrawal period was studied, with its own certainty rating.
The secretariat accepts this submission. The evidence exists, it is directly relevant, and it was not being assessed.
Post-withdrawal trajectory is now an assessed outcome wherever a withdrawal period was studied, rated on the same scale as the others. Where no withdrawal period was studied the outcome is recorded as not assessed.
Adverse event frequencies are given without the denominator or the exposure period
The draft on Tirzepatide is a substantial document and the respondent has confined this submission to one matter.
The draft reports adverse event frequencies as percentages. The respondent states that a percentage without a denominator and without an exposure period cannot be compared with any other figure, including the corresponding figure in the comparator arm.
The respondent proposes that every frequency carry the number of participants and the exposure period over which it was observed.
The secretariat accepts this submission. A frequency detached from its denominator is a number without a quantity.
Every reported frequency now carries the number of participants, the number of events and the exposure period, and comparator-arm figures are reported alongside rather than in a separate table.
The compound is supplied under names the monograph does not list
The respondent has read the draft monograph on Tirzepatide against a caseload in which incretin analogues are prescribed daily.
The respondent states that the compound is supplied under several trade names, research codes and transliterations, and that a reader holding a label bearing one of them will not find the monograph.
A list of names observed in supply, with the source of each observation, accompanied the submission.
The secretariat accepts this submission. A monograph a reader cannot find is not serving the reader.
The synonym list is extended to include every name the Institute can evidence from a document it holds, each recorded with its source. Names asserted without a supporting document are not added, and the distinction is stated at the head of the list.
The analytical section is longer than the clinical assessment it accompanies
The respondent read Tirzepatide in draft. The point applies to it and to the series generally.
The respondent states that the analytical section occupies more of the monograph than the assessment of clinical effect, and that the proportions imply the Institute considers the analytical question the more important one.
The respondent proposes that the analytical material be moved to the standards series and referenced rather than reproduced.
The secretariat accepts this submission in part. The general analytical material is moved to the standards series and referenced. The compound-specific material stays, because a reader holding a certificate for this compound needs to know what that certificate does and does not establish for this compound.
The analytical section is reduced to compound-specific content and cross-references the relevant standards for the general procedure, which shortens it substantially without removing what is not available elsewhere.
The document should not describe uses outside the approved indication
This submission concerns the draft on Tirzepatide. The respondent assesses incretin-class evidence for a national body and comments in a personal capacity.
The submission is made on behalf of a marketing-authorisation holder. It states that the draft describes uses of the compound that fall outside the approved indication, that such uses are not supported by the sponsor, and that describing them may be read as legitimising them.
The sponsor asks that the sections concerned be removed, or in the alternative that they carry a prominent statement that the sponsor does not support such use.
The secretariat does not accept this submission. The Institute records what is supplied and what is used, because a reader encountering a compound outside a regulated route is the reader most in need of an assessment of the evidence for it.
The sections remain. Every such section already states the regulatory status of the use described and states that the evidence for it is assessed separately from the evidence for the approved indication. The submission is published in full and identified as an industry submission.
The interaction section lists mechanisms rather than interactions
The respondent submits on Tirzepatide. The point would apply equally to any document in the series.
The section describes pathways by which an interaction could occur. It does not say which interactions have been observed, in what setting, or with what consequence. A reader dispensing alongside other therapy cannot act on a mechanism.
The respondent proposes that observed interactions be separated from theoretical ones, and that the theoretical ones be labelled as such.
The secretariat accepts the separation and declines to expand the section beyond the evidence.
The interaction section is now divided into interactions reported in clinical use and interactions predicted from mechanism, with the second labelled as prediction. Where neither exists the section says so in one line rather than being padded.
References cited on this page
References are numbered in order of first citation in this document. Each superscript in the text links to its entry below.
- International Organization for Standardization. ISO/IEC 17025:2017 General Requirements for the Competence of Testing and Calibration Laboratories. ISO/IEC Standard 2017;3rd edition. identifier not held by the Institute
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