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Use topical beta-blockers with care in newly diagnosed elderly patients, say U.K. glaucoma experts
In older patients, the drugs can cause serious side effects, including increased risk of airway obstruction, according to researchers.
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While topical beta-blockers are no longer the automatic choice for patients diagnosed with glaucoma or ocular hypertension, they are still prescribed in around half of all newly diagnosed patients in the United Kingdom. They should nonetheless be used with caution, argue U.K. glaucoma specialists.
Results of a population-based cohort study by researchers at the Institute of Ophthalmology in London confirm that topical beta-blockers can cause serious side effects in some elderly patients. James F. Kirwan, FRCOphth, and colleagues found that the risk of developing airway obstruction was 2.5 times higher in those exposed to the drugs than in the general population.
At 12 months after treatment with beta-blockers, 81 of 2,645 subjects (3.1%) with no prior airway obstruction developed new airway obstruction. This compares with 112 of 9,094 subjects (1.2%) in the control group of unexposed patients. The data indicate that one patient is harmed for every 55 treated with ophthalmic beta-blockers.
Beware subsequent problems
“The magnitude of the airways impairment as a result of exposure to ophthalmic beta-blockers was surprising. Our data indicate an attributable risk of 1,000 glaucoma patients developing asthma each year as a result of using topical beta-blockers. This is only a crude estimate, but nevertheless is a significant number of people. The true population risk may be higher, as there will be other patients with symptoms of airways obstruction who may never report to their doctor,” said Mr. Kirwan, first author of the study from the Institute of Ophthalmology and consultant ophthalmologist at Queen Alexandra Hospital, Portsmouth.
“The study findings reiterate earlier messages by other U.K. investigators,” Mr. Kirwan said. “That is, we need to be more careful with ophthalmic beta-blockers and be aware of the possibility of subsequent problems. Many of the reported clinical trials with beta-blockers involve patients who are younger and fitter than those typically seen in the general glaucoma population. We found that a significant proportion of patients were started on asthma treatment and continued to be prescribed their glaucoma beta-blocker drops.”
“The number needed to harm from the Kirwan study are very low indeed, but the results do not surprise me,” said Paul Diggory, FRCP, consultant geriatrician at Mayday University Hospital, Surrey. “In an earlier study we found that switching stable glaucoma patients on beta-blocker therapy to alternative drops led to a clinically significant improvement in respiratory function for approximately one-quarter of the study population.”
“As a geriatrician I avoid beta-blockers in the elderly,” Dr. Diggory said. “Patients with glaucoma should not be started on beta-blocker therapy without first conducting a spirometric investigation and having this checked once again on the return visit if started on such treatment. This should be done even in patients with no history of respiratory disease. It is a routine evaluation that can be carried out by nurses in the glaucoma clinic. An objective test is important, as many elderly patients have reduced subjective awareness of bronchospasm.”
Practice shifts
“My treatment approach in beginning therapy for glaucoma or significant ocular hypertension is to prescribe a prostaglandin analogue such as latanoprost rather than a topical beta-blocker,” said Andrew Brown, MD, a glaucoma specialist in a large medical practice in Leeds. “This means higher direct prescribing costs, but my experience in primary care and as a clinical assistant in secondary care confirms that such agents are generally more effective than beta-blockers and better tolerated in most patients.”
“Especially in the elderly, we must consider likely comorbidity that may be exacerbated with the use of topical beta-blockers and be aware of undiagnosed respiratory disease,” Dr. Brown added. “If considering an ophthalmic beta-blocker, I always check the patient’s pulse, blood pressure and respiratory function using spirometry before beginning treatment. A number of underlying problems directly linked to ophthalmic beta-blockers or other glaucoma medications often go unnoticed in general practice.”
Although treatment habits are slow to change, prescribing patterns in the UK have shifted dramatically in recent years. Latanoprost, the only prostaglandin analogue approved for first-line use, now accounts for more than half of all prescriptions written for patients newly diagnosed with glaucoma or ocular hypertension. Single-bottle combination treatments and the additional ophthalmic prostaglandin drugs travoprost and bimatoprost have broadened the choices available for secondary therapy.
“Topical beta-blockers are used less commonly than they once were because we now have other options. However, I still consider these agents to be highly useful glaucoma medications,” said Augusto Azuara-Blanco, FRCS(Ed), PhD, consultant ophthalmic surgeon at Aberdeen Royal Infirmary.
“In treating an individual with glaucoma, considerations include a full medical history, systemic factors such as possible history of COPD, asthma or bradycardia, and the stage and severity of glaucoma damage,” he added. “The target pressure is then considered. If I was looking for a 20% pressure reduction, then topical beta-blocker therapy without systemic contraindications is an excellent choice. If a reduction of 30% is required, then perhaps I’d consider an ophthalmic prostaglandin drug, as a beta-blocker may not achieve the target IOP.”
“Patients are always informed of the most common side effects of the glaucoma medications being offered and asked to volunteer which agent they would prefer,” Mr. Azuara-Blanco said. “In the case of beta-blockers, I tell patients these are usually well-tolerated, but some patients may complain of fatigue, shortness of breath, depression or impotence in the case of men, but these effects are reversible on treatment termination. With a first-line prostaglandin drug, the most common side effects are eyelash growth and iris color change, but systemically very safe.”
According to Mr. Azuara-Blanco, if beta-blockers are prescribed, patients should be closely monitored during follow-up, including direct questioning about any experiences of shortness of breath or use of inhalers.
“The take-home message from our study is that topical beta-blockers are not entirely safe and practitioners need to take care in prescribing them,” Mr. Kirwan said. “We are not arguing against the use of topical beta-blockers; they are generally well-tolerated, and enormous numbers of patients are successfully controlled with these drops. But we need to bear in mind the alternatives for initial therapy, particularly in the very elderly. Also, long-term data are not yet available for many of the newer medications.”
Benefits of nurse prescribing
Results of a recently-published audit of a nurse-led clinic at the Royal Victoria Infirmary in Newcastle upon Tyne showed that patients prescribed latanoprost had more satisfactory control at the first review visit and none of them suffered any side effects.
This is in contrast to those who received timolol initially. Nine of 31 patients had inadequate control, and four suffered side effects in the first month, requiring therapy change.
“Although the numbers were small, there was nonetheless a marked difference in the number of patient returns due to inadequate control or side effects,” said Michael Birch, FRCOphth, consultant ophthalmologist at the hospital.
“Because our nurses are preassessing and prescribing according to an established protocol, we have switched to using the prostaglandin analogue latanoprost as the first-line medication simply because we found it was safer and more effective,” Mr. Birch added. “Even outside the preassessment clinic, my experience has been that in elderly patients, monotherapy with a prostaglandin analogue is the preferred initial therapy. On the whole, elderly patients respond well and you avoid the need for excessive screening for potential systemic contraindications.
“Achieving long-term control with first-line treatment has many benefits in running a busy clinic, not least in reducing waiting times for appointments and improving compliance. Within the context of the National Health Service, the aim is to achieve the best result for as many patients as possible. Ophthalmic beta-blockers are still prescribed as useful second-line therapy, for example in poor responders, and also considered for some younger patients,” Mr. Birch said.
For Your Information:References:
- James F. Kirwan, FRCOphth, can be reached at Queen Alexandra Hospital, Southwick Hill Rd., Cosham, Portsmouth VO6 3LY, England; +(44) 239-228-6933; fax: +(44) 239-228-6440; e-mail: jfkirwan@ucl.ac.uk.
- Paul Diggory, FRCP, can be reached at Mayday University Hospital, London Rd., Thornton Heath, Surrey CR7 7YE, England; +(44) 208-401-3617; fax: +(44) 208-401-3620; e-mail: Pdiggory@aol.com.
- Andrew Brown, MD, can be reached at Tinshill Lane Surgery, No. 8 Tinshill Lane, Leeds LS16 7AP, England; tel: +(44) 113-267-3462; fax: +(44) 113-230-0402; e-mail: Andrew.Brown@gp-b86044.nhs.uk.
- Augusto Azuara-Blanco, FRCS(Ed), can be reached at the Department of Ophthalmology, Aberdeen Royal Infirmary, Aberdeen AB25 2ZN, Scotland; +(44) 122-468-1818; fax: +(44) 122-484-9156; e-mail: aazblanco@aol.com.
- Michael Birch, FRCOphth, can be reached at the Department of Ophthalmology, Claremont Wing, Royal Victoria Infirmary, Queen Victoria Rd., Newcastle upon Tyne NE1 4LP, England; +(44) 191-282-5448; fax: +(44) 019-227-5246; e-mail: birchmk@aol.com.
- Kirwan JF, Nightingale JA, et al. Beta-blockers for glaucoma and excess risk of airways obstruction: population based cohort study. Brit Med J. 2002; 325:1396-1397.
- Diggory P, Cassels-Brown A, et al. Avoiding unsuspected respiratory side-effects of topical timolol with cardioselective or sympathomimetic agents. Lancet. 1995; 345:1604-1606.
- Doctors Independent Network. Link, October 2002.
- Johnson ZK, Griffiths PG, Birch MK. Nurse prescribing in glaucoma. Eye. 2003;17:47-52.