Open questions — chronic obstructive pulmonary disease

Last curated: 2026-08-30

Stable identifiers are retained when questions are refined. Tier 1 questions could change practice and are designable now; Tier 2 questions need enabling methods, longer follow-up or mechanistic validation.

Tier 1 — practice-changing and designable now

OQ-1 — Which symptomatic/exposed case-finding strategy improves outcomes, not only diagnostic yield?

Questionnaires and micro-spirometry enrich confirmatory testing, but studies primarily measure new diagnoses rather than exacerbations, quality of life or net treatment change (Haroon 2015, PMID 26313400; Frith 2020, PMID 31950588).

OQ-2 — What repeat-spirometry rule should adjudicate values near FEV1/FVC 0.70?

Fixed-ratio simplicity trades against age-related misclassification; a prospective repeat-testing rule could measure stable labels, treatment changes and outcomes (Haynes 2023, PMID 37353330).

OQ-3 — Which PRISm/pre-COPD subgroup has a modifiable trajectory?

Early-state constructs are heterogeneous and lack validated intervention thresholds (Li 2025, PMID 40624819; Cadham 2024, PMID 38750492).

OQ-4 — Can repeated eosinophils guide ICS initiation and withdrawal better than a single count?

Eosinophil–outcome associations are continuous, while SUNSET suggests withdrawal risk rises in higher-count subgroups (Yun 2018, PMID 29709670; Chapman 2018, PMID 29779416).

OQ-5 — How should ICS and dupilumab be sequenced in type-2 COPD?

Dupilumab benefit was demonstrated on background triple therapy, so efficacy as an ICS-sparing strategy is unknown (Bhatt 2023, PMID 37272521; Bhatt 2024, PMID 38767614).

OQ-6 — Can eosinophil-guided systemic steroids safely reduce acute steroid exposure in hospitalized exacerbations?

CORTICO-COP supports reduced steroid exposure in hospitalized exacerbations, while STARR2 extends biomarker-directed treatment to primary care; severe-event precision and subgroup safety remain unresolved (Sivapalan 2019, PMID 31122894; Ramakrishnan 2024, PMID 37924830).

OQ-7 — Which discharge bundle prevents 30- and 90-day readmission?

Medication reconciliation, early follow-up and rehabilitation are bundled variably; component effects remain unclear (MacLeod 2021, PMID 33893708; Puhan 2016, PMID 27930803).

OQ-8 — What post-exacerbation PR start window maximizes benefit and acceptability?

Post-event PR evidence is heterogeneous and real-world uptake is low (Puhan 2016, PMID 27930803).

OQ-9 — Can minimal-equipment or hybrid PR match center-based outcomes without widening digital inequity?

Minimal-equipment programs improve outcomes, but comparative durability and access effects need pragmatic trials (Cheng 2023, PMID 37140475).

OQ-10 — Which moderate/exertional desaturation phenotype benefits from ambulatory oxygen?

LOTT was neutral for death/first hospitalization; individual functional response may not predict durable patient-important benefit (Albert 2016, PMID 27783918).

OQ-11 — What PaCO2 threshold and timing best select long-term home NIV after an exacerbation?

HOT-HMV supports persistent post-event hypercapnia, but selection and titration differ across services (Murphy 2017, PMID 28528348; Ergan 2019, PMID 31467119).

OQ-12 — Which eligible emphysema patients should receive valves rather than LVRS?

CELEB directly randomized 88 people eligible for either procedure and found no significant difference in 12-month i-BODE improvement; only 49 had complete primary outcomes, leaving patient-level selection and precision unresolved (Buttery 2023, PMID 36796833).

OQ-13 — Which CT rule predicts durable five-year valve benefit and pneumothorax risk?

Fissure integrity predicts initial response, while long-term durability and early pneumothorax remain variable (Criner 2018, PMID 29787288; Koster 2022, PMID 35562097).

OQ-14 — Does universal COPD testing for AATD improve case detection and family outcomes cost-effectively?

Guidelines recommend broad testing, yet detection remains incomplete (Miravitlles 2017, PMID 29191952; Brantly 2020, PMID 32306990).

OQ-15 — Which severe AATD population obtains survival or exacerbation benefit from augmentation?

CT-density evidence and observational survival associations do not fully resolve hard outcomes (Strange 2018, PMID 29794204; Fraughen 2023, PMID 37624745).

OQ-16 — Can integrated cardiopulmonary assessment reduce misclassified COPD exacerbations?

Cardiac and respiratory causes overlap, and COPD deaths frequently involve cardiovascular disease (Halpin 2024, PMID 39078244).

OQ-17 — Which oxygen-service design preserves mobility and reduces treatment burden?

Equipment burden is recognized but rarely a primary randomized endpoint (Taichman 2024, PMID 39254439).

OQ-18 — Which stigma intervention improves help-seeking or rehabilitation uptake?

COPD-specific stigma measurement is early; a PubMed search on 2026-08-30 retrieved no intervention trial linking stigma reduction to help-seeking or rehabilitation uptake (Woo 2023, PMID 37084465).

Tier 2 — enabling science and longer horizons

OQ-19 — Which small-airway measurement best predicts incident obstruction?

Small-airway loss can precede conventional COPD, but thresholds and longitudinal treatment relevance are unsettled (Verleden 2024, PMID 38055196).

OQ-20 — Are machine-derived CT emphysema subtypes reproducible and treatment-predictive?

Unsupervised clusters describe anatomy but need external and prospective validation (Angelini 2023, PMID 37268414).

OQ-21 — Which tissue immune communities sustain emphysema after smoking cessation?

Spatial transcriptomics identifies B-cell-rich structures without proving causation (Rojas-Quintero 2024, PMID 37934672).

OQ-22 — Why did IL-4Rα blockade outperform IL-5 strategies in eosinophilic COPD?

Mepolizumab effects were modest/inconsistent while dupilumab phase 3 results replicated (Pavord 2017, PMID 28893134; Bhatt 2024, PMID 38767614).

OQ-23 — Can neutrophilic inflammation be treated without increasing infection?

Neutrophils contribute proteases and mucus biology but are indispensable host defense (Brightling 2019, PMID 31073084).

OQ-24 — Can human alveolar repair be activated safely?

FGF10 reversed experimental emphysema in mice; translation must address fibrosis, cancer and delivery (Hadzic 2023, PMID 37884305).

OQ-25 — How much COPD arises from low attained lung function rather than accelerated adult decline?

Life-course development and aging provide multiple routes to the same late spirometry (Bush 2016, PMID 28005431).

OQ-26 — Can ancestry-diverse polygenic prediction add value beyond exposure, spirometry and CT?

COPD GWAS discovery is substantial but clinical calibration and ancestry representation are inadequate (Silverman 2020, PMID 31730394).

OQ-27 — What exposure reduction from clean household energy changes lung-function trajectory?

Biomass associations are heterogeneous, and intervention adoption/exposure separation is difficult (Kurmi 2010, PMID 20335290; Pathak 2020, PMID 30754998).

OQ-28 — Can MRI provide a standardized multicenter functional surrogate?

Regional ventilation/perfusion imaging is mechanistically attractive but not validated for treatment decisions (Elbehairy 2024, PMID 38548292).

OQ-29 — Which regenerative-cell product has a defined mechanism and acceptable long-term safety?

Early registries include bronchial basal-cell and small-mobile-cell approaches, but completed status is not efficacy (NCT03021681; NCT06986070).

OQ-30 — What COPD outcome core set should all trials report?

Patient-reported outcomes are selected inconsistently, frustrating meta-analysis and patient interpretation (Afroz 2020, PMID 32801678).

OQ-31 — Can intervention be matched to the two major lung-function trajectories before fixed obstruction appears?

Approximately half of COPD arose from low attained early-adult FEV1 and half from accelerated decline after normal attainment; the latter route had higher all-cause mortality (HR 1.93, 95% CI 1.14–3.26) in long-term follow-up (Lange 2015, PMID 26154786; Marott 2020, PMID 32289231). A designable platform could stratify by repeated early-adult spirometry and randomize exposure, asthma or development-focused interventions before both routes converge on late obstruction.

OQ-32 — Is CT mucus-plug burden a modifiable causal trait or only a severity marker?

Mortality rose from 34.0% with no plugged segments to 54.1% with at least three over median 9.5 years, but observational adjustment cannot show that clearing plugs changes outcomes (Diaz 2023, PMID 37210745). Trials should require plug reduction plus exacerbation, activity and mortality-linked outcomes, not imaging response alone.

OQ-33 — Which head-to-head biologic sequence maximizes net benefit in type-2 COPD?

Dupilumab produced replicated benefit, MATINEE showed a smaller mepolizumab exacerbation effect without significant symptom/QoL improvement, benralizumab primary phase 3 comparisons were neutral, and COURSE did not establish broad tezepelumab efficacy (Bhatt 2024, PMID 38767614; Sciurba 2025, PMID 40305712; Criner 2019, PMID 31112385; Singh 2025, PMID 39653044). Indirect cross-trial comparison cannot establish sequence, switching or ICS-sparing effects.

OQ-34 — Where should ensifentrine sit relative to LABA/LAMA, triple therapy and rehabilitation?

ENHANCE replicated 87–94 mL FEV1 AUC benefit and moderate/severe-event rate ratios of 0.64 and 0.57, but symptom and SGRQ effects did not replicate across both trials (Anzueto 2023, PMID 37364283). Pragmatic factorial comparison on contemporary background treatment should measure exacerbations, symptoms, device burden, cost and discontinuation.

OQ-35 — Can an integrated frailty–bone–rehabilitation pathway improve outcomes beyond separate screening?

Frailty prevalence pooled at 32.07% and carried mortality HR 1.68, while osteoporosis prevalence pooled at 38%; both estimates varied by population and definition (Wang 2023, PMID 37173728; Chen 2019, PMID 31352034). A trial could randomize systematic identification plus nutrition, resistance training, falls and bone treatment against usual fragmented care.

OQ-36 — Does targeted cardiovascular surveillance after exacerbation prevent events?

Cardiovascular-event hazard was 3.8-fold higher in the first 30 days after an exacerbation and 9.9-fold higher after a hospitalized event in SUMMIT participants with cardiovascular disease or risk (Kunisaki 2018, PMID 29442524). The association identifies a designable window but not the effective surveillance or preventive intervention.

OQ-37 — Can oscillometry improve diagnostic access without substituting one threshold problem for another?

Small cross-sectional studies report AUCs near 0.8 against spirometry or CT, but cutoffs vary with BMI and positive predictive value can be low (Chaiwong 2020, PMID 33121279; Chen 2024, PMID 38187302; Klitgaard 2023, PMID 36836082). A pragmatic diagnostic trial should compare completed diagnostic pathways, false labels, cost and downstream outcomes—not only same-day discrimination.

OQ-38 — Can airway NET inhibition reduce virus-triggered exacerbation without impairing host defense?

Human rhinovirus challenge links NET burden to exacerbation severity and mouse NETosis/DNase experiments support causal immunopathology, but NETs also contain infection (Katsoulis 2024, PMID 38982052; Keir 2022, PMID 35197267). Early trials need pathogen clearance and secondary infection as co-primary safety domains.

OQ-39 — Which treatment-burden intervention increases capacity rather than merely transferring work home?

Qualitative syntheses identify fragmented pathways, navigation work, isolation and caregiver capacity as determinants of COPD treatment burden (Lippiett 2019, PMID 30813114; May 2016, PMID 27707824). Co-designed trials should measure patient and caregiver time, abandonment of care, social participation and equity alongside utilization.

OQ-40 — Which post-exacerbation cardiovascular intervention matches the timing and phenotype of risk?

A 213,466-person cohort found the cardiovascular hazard highest in days 1–14 after severe events (HR 14.5, 95% CI 12.2–17.3) but peaking in days 14–30 after moderate events, with different component outcomes (Graul 2024, PMID 38127850). This sharpens OQ-36 from surveillance in general to severity- and time-specific prevention.

OQ-41 — Which component of an early-diagnosis pathway changes outcomes in COPD specifically?

Case-finding plus pulmonologist and educator care reduced respiratory health-care use by 52%, but the randomized population combined newly diagnosed asthma and COPD and bundled diagnosis with treatment (Aaron 2024, PMID 38767248). A COPD-specific factorial design should separate prescreening, confirmatory testing, clinician expertise and self-management support.

OQ-42 — Is a Proteobacteria-dominant airway microbiome a cause, consequence or treatment marker?

Longitudinal sampling links viral events and bacterial dominance to exacerbation, while stable Proteobacteria dominance predicts mortality (Bouquet 2020, PMID 32228581; Dicker 2021, PMID 32353489). Perturbation studies must distinguish pathogen clearance from ecological harm and stratify antibiotics, ICS exposure and bronchiectasis.

OQ-43 — Does smoking status identify an IL-33-pathway-responsive COPD endotype?

Itepekimab missed its overall exacerbation endpoint but showed a prespecified former-smoker signal, whereas astegolimab also missed its overall endpoint (Rabe 2021, PMID 34302758; Yousuf 2022, PMID 35339234). Replication must test a treatment-by-smoking-status interaction rather than treating the subgroup estimate as efficacy.

OQ-44 — Can ambulatory-oxygen benefit be predicted jointly with real-world acceptability?

Short-term quality of life improved in a small crossover trial, yet acute exercise response did not predict longer response and 41% of acute or short-term responders declined continued oxygen (Eaton 2002, PMID 12212960). Trials should co-model physiological response, device weight, mobility, stigma and abandonment.

OQ-45 — Which inhaler errors are causally important and correctable?

Nineteen COPD studies provided only weak, confounded evidence linking aggregate error counts to clinical outcomes, with adherence usually unmeasured (Halpin 2024, PMID 38626929). Sensor-supported trials should randomize correction of prespecified critical errors and measure exacerbations and quality of life, not technique scores alone.

Dots not yet connected

#	Dot A	Dot B	The missing junction	Powers
1	Pre-COPD small-airway abnormality	Smoking/clean-air intervention	Randomize exposure intervention before obstruction using sensitive physiology	OQ-3, OQ-19, OQ-27
2	CT mucus plugs	Dupilumab response	Test whether plug burden predicts IL-4Rα benefit beyond eosinophils	OQ-5, OQ-22
3	Eosinophil-guided acute steroids	Long-term ICS/biologic selection	Use event biology to personalize chronic prevention	OQ-4, OQ-5, OQ-6
4	Hyperinflation reduction	Cardiovascular dysfunction	Test whether valves/LVRS improve clinical cardiac outcomes	OQ-12, OQ-16
5	Oxygen equipment burden	Rehabilitation participation	Co-design portable oxygen around PR and life-space outcomes	OQ-9, OQ-10, OQ-17
6	AATD cascade testing	Smoking prevention in relatives	Measure long-term behavior and disease avoided after genetic detection	OQ-14, OQ-15
7	PR access failure	COPD stigma	Test whether peer-led stigma intervention improves PR uptake	OQ-9, OQ-18
8	Spatial immune niches	CT emphysema progression	Link tissue-resolved immune state to longitudinal regional destruction	OQ-20, OQ-21
9	Never-smoker COPD	Polygenic/lung-growth trajectories	Build ancestry-diverse causal strata beyond “non-smoking”	OQ-25, OQ-26, OQ-27
10	Home NIV physiology	Caregiver/equipment workload	Optimize PaCO2 reduction jointly with treatment burden	OQ-11, OQ-17
11	Digital exacerbation prediction	Misclassified cardiac events	Adjudicate whether alerts detect COPD biology or multimorbidity	OQ-7, OQ-16
12	Trial PRO inconsistency	Patient advocacy priorities	Establish a patient-governed COPD core outcome set	OQ-18, OQ-30
13	Early-adult spirometric trajectory	Exposure-specific prevention	Randomize prevention before low attainment and rapid decline converge	OQ-3, OQ-25, OQ-31
14	CT mucus-plug mortality signal	Mucolytic/biologic/airway-clearance intervention	Require imaging and patient-important causal validation	OQ-5, OQ-22, OQ-32
15	Replicated type-2 biologic effects	ICS withdrawal and drug burden	Head-to-head sequencing and steroid-sparing strategy	OQ-4, OQ-5, OQ-33
16	Ensifentrine physiology/event signal	PR and dual/triple inhaler optimization	Factorial comparative-effectiveness pathway	OQ-9, OQ-30, OQ-34
17	Frailty and osteoporosis prevalence	Rehabilitation/nutrition/bone treatment	Test a unified pathway rather than parallel referrals	OQ-7, OQ-9, OQ-35
18	Post-exacerbation cardiac-risk window	Discharge bundles and remote monitoring	Randomize surveillance/prevention with adjudicated cardiopulmonary events	OQ-7, OQ-16, OQ-36
19	Low-effort oscillometry	Quality-assured spirometry pathways	Test pathway completion and misclassification, not device discrimination alone	OQ-3, OQ-19, OQ-37
20	Virus-induced NET pathology	Infection-preserving anti-inflammatory treatment	Couple NET target engagement to pathogen-clearance safety	OQ-7, OQ-23, OQ-38
21	Treatment workload	Telerehabilitation and home monitoring	Determine whether remote care expands capacity or shifts labor to families	OQ-9, OQ-17, OQ-39
22	Severity-specific cardiovascular timing	Post-exacerbation prevention	Match intervention and start time to moderate versus severe event trajectories	OQ-16, OQ-36, OQ-40
23	Outcome-positive mixed-disease case-finding	COPD diagnostic thresholds	Separate the value of detection from the value of specialist/educator treatment	OQ-3, OQ-37, OQ-41
24	Airway microbial state	Anti-inflammatory and antibiotic exposure	Test whether altering ecology changes events without impairing host defense	OQ-7, OQ-23, OQ-42
25	Former-smoker alarmin signal	Tissue and blood endotyping	Prospectively validate smoking status as biology, proxy or chance subgroup	OQ-22, OQ-23, OQ-43
26	Ambulatory-oxygen physiological response	Treatment workload and life-space mobility	Predict net benefit including whether equipment is actually used	OQ-10, OQ-17, OQ-44
27	Device-specific critical errors	Objective adherence	Identify correctable causal failures rather than counting all technique deviations	OQ-8, OQ-17, OQ-45