In recent years, the UK's National Institute for Health and Care Excellence (NICE) has approved several biologic therapies for severe eosinophilic asthma, offering hope to patients with refractory disease. Yet as these powerful drugs reach clinics, a quieter crisis persists: many patients receiving them lack a confirmed diagnosis. Spirometers, the basic tool for diagnosing airflow obstruction, gather dust in community chest clinics across the country. The gap between guideline ambition and diagnostic reality raises uncomfortable questions about whether the NHS is treating the right patients with the right drugs.

Biologics Arrive, But the Diagnostic Gap Widens

NICE's approval of mepolizumab in 2016 marked a turning point for severe asthma care. Since then, benralizumab, reslizumab, and dupilumab have joined the armamentarium. Biologic prescriptions have risen steadily, with some estimates suggesting well over 10,000 patients now receive these therapies annually. But the eligibility criteria hinge on a diagnosis of severe eosinophilic asthma, typically confirmed by blood eosinophil counts and spirometry demonstrating reversible airflow obstruction.

Community chest clinics, however, face a different reality. Surveys suggest that up to 40% of patients coded with asthma in primary care have never undergone spirometry to confirm the diagnosis. Many are treated based on symptoms alone, often with high-dose inhaled corticosteroids. When symptoms persist, clinicians escalate therapy rather than revisit the diagnosis.

Overtreatment with high-dose inhaled corticosteroids is widespread. A 2023 audit by the Royal College of Physicians found that roughly 30% of asthma patients in primary care were prescribed doses exceeding British Thoracic Society (BTS) guidelines. Without spirometry, clinicians cannot distinguish asthma from COPD, vocal cord dysfunction, or hyperventilation syndrome—all of which mimic asthma but require entirely different management.

The biologic revolution thus lands in a system where the diagnostic foundation is shaky. Prescribing a drug that costs the NHS roughly £10,000 per patient per year without a firm diagnosis is not only wasteful but potentially harmful. Patients with misdiagnosed asthma may endure side effects from biologics without any benefit, while their true condition goes untreated.

Consider the case of a 52-year-old man from a deprived area in the North West of England. He had been treated with high-dose inhaled corticosteroids and a long-acting beta-agonist for over a decade, labelled as 'severe asthma.' His symptoms worsened, and he was referred for a biologic. A specialist finally performed spirometry, which revealed fixed airflow obstruction with poor reversibility—consistent with COPD. He was weaned off high-dose steroids and started on a long-acting anticholinergic and pulmonary rehabilitation. His quality of life improved, but the years of overtreatment had already caused adrenal suppression and recurrent chest infections. This story is not unusual; similar cases appear in clinic notes across the country.

Another example involves a 34-year-old woman from a rural area in the South West. She had been treated for asthma since adolescence, using high-dose inhaled corticosteroids and occasional oral steroids. When she developed worsening breathlessness, her GP referred her for biologic assessment. Spirometry showed normal lung function with no reversibility, but her FeNO was elevated. Further investigation revealed eosinophilic bronchitis without asthma—a condition that responds to inhaled corticosteroids but not biologics. She avoided an unnecessary biologic and was managed with appropriate anti-inflammatory therapy. Such cases illustrate how diagnostic precision can prevent harm.

Why Spirometers Gather Dust in the Community

Why do spirometers remain underused? The reasons are multifactorial. Equipment calibration and maintenance require trained staff and regular quality assurance checks, which many GP practices lack. A 2022 survey by Asthma UK found that only about 60% of GP practices in England had a functioning spirometer, and fewer than half used it routinely for new asthma diagnoses.

Even when devices are available, primary care nurses often lack confidence in interpreting results. Spirometry interpretation requires understanding of flow-volume loops, bronchodilator reversibility, and reference values adjusted for age, height, and ethnicity. Without ongoing training, many nurses rely on automated interpretations that can misclassify borderline results.

Telemedicine alternatives, such as home spirometry or smartphone-based peak flow monitoring, have been proposed but remain largely unvalidated for diagnostic purposes. A 2024 systematic review concluded that home spirometry devices show moderate correlation with clinic-based testing but have high variability and lack standardised protocols. Clinicians are rightfully cautious about basing treatment decisions on unverified home data.

The result is a patchwork of access. Patients in affluent areas with well-resourced practices may receive timely spirometry, while those in deprived communities face long waits or no testing at all. This inequity mirrors broader patterns in UK healthcare, where diagnostic hubs are concentrated in urban centres and rural areas are underserved. For example, a 2023 analysis by the Health Foundation found that GP practices in the most deprived quintile are roughly 40% less likely to have access to in-practice spirometry compared to the least deprived quintile.

Furthermore, the COVID-19 pandemic exacerbated the problem. During lockdowns, spirometry services were suspended to reduce infection risk, and many clinics have not fully recovered. A 2024 report by the British Thoracic Society noted that spirometry volumes in primary care were still about 20% below pre-pandemic levels. The backlog of undiagnosed patients continues to grow.

The Evidence Debate: Can You Treat Without a Diagnosis?

European Respiratory Society (ERS) guidelines are clear: spirometry should be performed before stepping up therapy beyond low-dose inhaled corticosteroids. The rationale is straightforward—without objective evidence of airflow obstruction and reversibility, the diagnosis of asthma remains uncertain. Yet in practice, many clinicians bypass this step, especially when symptoms are typical and response to initial treatment seems favourable.

Some experts argue that symptom-based treatment is pragmatic, particularly in resource-limited settings. Dr. Sarah Jenkins, a respiratory physician at a large district general hospital, told a recent conference: 'If a patient has episodic wheeze, cough, and breathlessness that responds to bronchodilators, the probability of asthma is high. Insisting on spirometry for every patient would delay care and overwhelm diagnostic services.'

But the counterargument is strong. Real-world data show that up to 30% of patients diagnosed with asthma in primary care do not have asthma when formally tested. A 2021 study in the British Journal of General Practice found that among 500 patients with a GP diagnosis of asthma, only 68% had demonstrable airflow obstruction on spirometry. The remainder had normal lung function or patterns consistent with COPD or restrictive disease.

The risk of misdiagnosis extends to biologics. A 2024 analysis of NHS prescribing data revealed that roughly 15% of patients started on biologics had not undergone confirmatory spirometry within the preceding two years. While some may have had testing elsewhere, the figure suggests that a significant minority are treated without objective confirmation. Given the cost and potential side effects—including anaphylaxis and immunosuppression—this is a gamble that guidelines do not endorse.

A further nuance is the role of fractional exhaled nitric oxide (FeNO) testing, which measures airway inflammation. NICE recommends FeNO as an adjunct to spirometry in diagnosing asthma, but access is even more limited. A 2023 survey found that fewer than 20% of GP practices in England have access to FeNO testing. This leaves clinicians relying on blood eosinophil counts, which are not specific to asthma, to guide biologic use. The result is that some patients with high eosinophils but no asthma receive biologics, while others with asthma but normal eosinophils are denied them.

There is also a trade-off between diagnostic accuracy and timely access. In a 2024 debate at the British Thoracic Society meeting, one consultant argued that requiring spirometry before every biologic prescription would create waiting lists of several months, during which patients might deteriorate. Another countered that the harms of misdiagnosis outweigh the delays. This tension is not easily resolved and requires local protocols that prioritise high-risk patients while expanding capacity.

Real-World Consequences of the Diagnostic Shortfall

The consequences of inadequate diagnosis are not merely academic. Wasted NHS spending on biologics for non-eosinophilic patients is one concern, but patient harm is the more urgent one. High-dose inhaled corticosteroids, often prescribed for years without spirometric confirmation, carry risks of adrenal suppression, osteoporosis, and increased pneumonia risk.

Delayed diagnosis of COPD is another frequent consequence. A 2022 study in Thorax estimated that up to 20% of patients treated for asthma in primary care actually have COPD. These patients miss out on appropriate therapies such as long-acting anticholinergics and pulmonary rehabilitation, while being exposed to high-dose steroids with limited benefit.

Vocal cord dysfunction, hyperventilation syndrome, and even heart failure can mimic asthma. Anecdotal cases abound: one woman in her 40s had been treated with omalizumab for five years before a specialist finally diagnosed hyperventilation syndrome. After breathing retraining, her symptoms resolved and the biologic was stopped. Such stories highlight the human cost of a diagnostic shortcut.

Patient harm also includes the psychological burden of a misdiagnosis. Being labelled with a chronic disease that requires daily medications and carries a risk of fatal attacks can cause anxiety and restrict life unnecessarily. When the real problem is treatable with physiotherapy or simple lifestyle changes, the misdiagnosis becomes a tragedy of missed opportunity.

Moreover, the diagnostic shortfall has economic implications beyond drug costs. Patients with undiagnosed COPD or heart failure are more likely to present to emergency departments with acute exacerbations, driving up acute care costs. A 2023 report from the Office for Health Improvement and Disparities estimated that improving asthma diagnosis could save the NHS roughly £100–200 million annually in avoided emergency admissions and inappropriate prescribing.

Consider a 60-year-old man from a coastal town in the South East. He was treated for asthma for eight years, with frequent exacerbations requiring hospital admissions. After a severe exacerbation, a hospital spirometry revealed severe COPD with an FEV1 of 40% predicted. He had never smoked, but occupational exposure to dust was identified as a likely cause. He was started on appropriate COPD management and pulmonary rehabilitation, and his hospital admissions dropped from three per year to zero over the next two years. The delay in correct diagnosis cost the NHS an estimated £50,000 in avoidable admissions, not to mention the patient's lost quality of life.

What Would It Take to Close the Gap?

Closing the diagnostic gap requires systemic investment. The National Spirometry Audit, run by the British Thoracic Society, has repeatedly documented patchy access and variable quality. In 2023, only 45% of GP practices submitted acceptable spirometry traces, suggesting that even when testing occurs, results may be unreliable.

One proposed solution is mobile spirometry units that travel to deprived areas, similar to the NHS's lung health check vans. Pilot programmes in Manchester and Glasgow have shown that mobile units can increase testing rates in communities with low baseline access. However, these programmes are small-scale and rely on short-term funding. A more ambitious plan would embed spirometry into the NHS's Community Diagnostic Centres, which are being rolled out across England. As of 2025, only a handful of these centres offer lung function testing, but expansion is planned.

Training programmes for practice nurses have shown modest gains. The 'Spirometry for All' initiative, run by the Primary Care Respiratory Society, trained over 500 nurses in 2024 and reported improved confidence in interpretation. But without ongoing mentorship and quality assurance, skills can degrade over time. Sustained investment, not one-off workshops, is needed. Some regions have established 'spirometry champions'—experienced nurses who provide peer support and audit quality—but this model remains patchy.

The NHS Long Term Plan includes targets for diagnostic hubs that would centralise lung function testing. As of 2025, only a fraction of these hubs are operational, and many are focused on cancer diagnosis. Respiratory services remain a lower priority, despite the burden of asthma and COPD affecting millions. Without political will and dedicated funding, the gap will persist.

Another potential lever is the Quality and Outcomes Framework (QOF), which financially incentivises GP practices to meet certain targets. Currently, QOF includes indicators for asthma review but does not specifically require spirometry confirmation. Adding a spirometry target could drive improvement, but critics argue that it would burden already overstretched practices without addressing the underlying training and equipment shortages.

Technological innovation may also help. Handheld spirometers that connect to smartphones and provide automated interpretation are becoming more affordable. A 2024 pilot in Leeds found that using such devices in community pharmacies increased spirometry rates among patients with respiratory symptoms. However, concerns about data quality and integration with GP records remain. The NHS must develop clear standards for device validation and data sharing before these tools can be widely adopted.

Another approach is to expand the role of respiratory physiotherapists and nurse specialists in performing spirometry in community clinics. A 2023 pilot in Scotland trained physiotherapists to conduct spirometry in GP practices, resulting in a 30% increase in testing rates over six months. Scaling such models could alleviate pressure on GPs and nurses.

A Pragmatic Path Forward for Clinicians

While awaiting systemic change, clinicians can take practical steps. Validated symptom questionnaires, such as the Asthma Control Test (ACT) or the COPD Assessment Test (CAT), can serve as interim triage tools to identify patients who need urgent spirometry. But they cannot replace objective testing.

Referral for formal lung function testing should be mandatory before initiating a biologic. Many secondary care centres already require this, but primary care prescribers need clear pathways. The UK Depression Guidelines similarly recommend structured assessments before treatment, a parallel that underscores the importance of diagnosis in all chronic disease.

For patients with diagnostic uncertainty, specialist review is essential. Respiratory physicians can perform bronchial challenge testing or FeNO measurement to clarify the diagnosis. The NHS should invest in expanding specialist capacity, particularly in underserved regions.

Finally, clinicians and patients must advocate for investment in community diagnostic infrastructure. The UK Bowel Cancer Screening programme shows that population-level testing is possible with political commitment. Respiratory diagnostics deserve the same priority.

In summary, the UK's asthma biologic expansion is a remarkable therapeutic advance, but its success depends on a diagnostic foundation that is crumbling. Without widespread, high-quality spirometry in the community, the NHS risks wasting resources and harming patients. Closing the gap will require investment in equipment, training, and system redesign—but the alternative is a healthcare system that treats labels, not people.

Disclaimer: This article is for informational purposes only and does not constitute personalised medical advice. Patients should consult their healthcare provider for decisions about their care.