Exploiting the potential of routine data to better understand the disease burden posed by allergic disorders

Deriving a Standardised Recommended Respiratory Disease Codelist Repository for Future Research

Background

Electronic health record (EHR) databases provide rich, longitudinal data on interactions with healthcare providers and can be used to advance research into respiratory conditions. However, since these data are primarily collected to support health care delivery, clinical coding can be inconsistent, resulting in inherent challenges in using these data for research purposes.

Methods

We systematically searched existing international literature and UK code repositories to find respiratory disease codelists for asthma from January 2018, and chronic obstructive pulmonary disease and respiratory tract infections from January 2020, based on prior searches. Medline searches using key terms provided in article lists. Full-text articles, supplementary files, and reference lists were examined for codelists, and codelists repositories were searched. A reproducible methodology for codelists creation was developed with recommended lists for each disease created based on multidisciplinary expert opinion and previously published literature.

Results

Medline searches returned 1126 asthma articles, 70 COPD articles, and 90 respiratory infection articles, with 3%, 22% and 5% including codelists, respectively. Repository searching returned 12 asthma, 23 COPD, and 64 respiratory infection codelists. We have systematically compiled respiratory disease codelists and from these derived recommended lists for use by researchers to find the most up-to-date and relevant respiratory disease codelists that can be tailored to individual research questions.

Conclusion

Few published papers include codelists, and where published diverse codelists were used, even when answering similar research questions. Whilst some advances have been made, greater consistency and transparency across studies using routine data to study respiratory diseases are needed.

Prescription rates of adrenaline auto-injectors for children in UK general practice: a retrospective cohort study

BACKGROUND

Adrenaline auto-injectors (AAI) should be provided to individuals considered to be at high risk of anaphylaxis. There is some evidence that the rate of AAI prescription is increasing, but the true extent has not been previously quantified.

AIM

To estimate the trends in annual GP-issued prescriptions for AAI among UK children between 2000 and 2012.

DESIGN AND SETTING

Retrospective cohort study using data from primary care practices that contributed to The Health Improvement Network (THIN) database.

METHOD

Children and young people aged between 0-17 years of age with a prescription for AAIs were identified, and annual AAI device prescription rates were estimated using Stata (version 12).

RESULTS

A total of 1.06 million UK children were identified, providing 5.1 million person years of follow-up data. Overall, 23 837 children were deemed high risk by their GPs, and were prescribed 98 737 AAI devices. This equates to 4.67 children (95% confidence interval [CI] = 4.66 to 4.69), and 19.4 (95% CI = 19.2 to 19.5) devices per 1000 person years. Between 2000 and 2012, there has been a 355% increase in the number of children prescribed devices, and a 506% increase in the total number of AAI devices prescribed per 1000 person years in the UK. The number of devices issued per high-risk child during this period has also increased by 33%.

CONCLUSION

The number of children being prescribed AAI devices and the number of devices being prescribed in UK primary care between 2000 and 2012 has significantly increased. A discussion to promote rational prescribing of AAIs in the NHS is needed.

Hormonal contraceptives and asthma in women of reproductive age: analysis of data from serial national Scottish Health Surveys

OBJECTIVES

Sex steroid hormones may explain known gender-related variations in asthma prevalence and clinical manifestation. We investigated the relationship between use of hormonal contraceptives and asthma in women, and assessed evidence of biological interaction between use of hormonal contraceptives and body mass index in this relationship.

DESIGN

Population-based analysis using data from serial (i.e. 2003, 2008 and 2010) Scottish Health Surveys.

SETTING

Random samples of the Scottish general population.

PARTICIPANTS

A total of 3257 non-pregnant, 16-45-year-old women.

EXPOSURE

Current use of hormonal contraceptives.

MAIN OUTCOME MEASURES

Self-reported current physician-diagnosed asthma, current wheezing symptoms, wheezing attacks and treatment for asthma or wheeze.

RESULTS

Women comprising 30.9% (95% confidence interval 29.3-32.5) were currently using any hormonal contraceptive and current physician-diagnosed asthma was present in 6.5% (95% confidence interval 5.7-7.4). Use of any hormonal contraceptive was associated with reduced risk of current physician-diagnosed asthma (odds ratio 0.68; 95% confidence interval 0.47-0.98) and receiving ≥3 asthma care episodes (odds ratio 0.45; 95% confidence interval 0.25-0.82), but the evidence was equivocal for wheezing attacks. Use of hormonal contraceptives among overweight or obese women was non-statistically significantly associated with asthma, but there was 42-135% increased risk in overweight and obese non-contraceptive using women.

CONCLUSIONS

Use of hormonal contraceptives may reduce asthma exacerbations and number of care episodes. Overweight and obese non-contraceptive-using women may be at increased risk of asthma. Prospective studies are now needed to confirm these findings. Both oestrogen and progesterone may stimulate smooth airway muscle function and inhibit the activities of TH2 responses. Future studies should investigate these underlying mechanisms.

Development and validation of a model to predict the 10-year risk of general practitioner-recorded COPD

BACKGROUND

There is increasing interest in the earlier detection of, and intervention in, patients at highest risk of developing chronic obstructive pulmonary disease (COPD).

AIMS

The objective of this research was to develop and validate a risk prediction model for general practitioner (GP)-recorded diagnosis of COPD.

METHODS

We used data from 239 Scottish GP practices; two-thirds were randomly allocated to a derivation cohort and the other third to a validation cohort. We included patients aged 35-74 years at the cohort entry date, and excluded patients with a recorded diagnosis of COPD prior to the entry date and with missing data on smoking status.

RESULTS

There were 480,903 patients in the derivation cohort and 247,755 in the validation cohort. The incidence of COPD in the total cohort was 5.53/1,000 patient-years of follow-up (95% confidence interval (CI), 5.46-5.60). In the derivation cohort, the COPD risk for ever- versus never-smokers was substantially higher in women (hazard ratio (HR)=9.61, 95% CI, 8.92-10.34) than in men (HR=6.72, 95% CI, 6.19-7.30). Other risk factors for both sexes were level of deprivation and a previously recorded asthma diagnosis. In the validation cohort, the model discriminated well between patients who did and those who did not develop COPD: area under the receiver operating characteristics curve=0.845 (95% CI, 0.840-0.850) for females and 0.832 (95% CI, 0.827-0.837) for males.

CONCLUSIONS

We have developed and validated the first risk prediction model for COPD, which has the major advantage of being populated entirely by routinely collected data and consequently may be used for clinical practice.

The epidemiology of anaphylaxis in Europe: a systematic review

BACKGROUND

Anaphylaxis is an acute, potentially fatal, multi-organ system, allergic reaction caused by the release of chemical mediators from mast cells and basophils. Uncertainty exists around epidemiological measures of incidence and prevalence, risk factors, risk of recurrence, and death due to anaphylaxis. This systematic review aimed to (1) understand and describe the epidemiology of anaphylaxis and (2) describe how these characteristics vary by person, place, and time.

METHODS

Using a highly sensitive search strategy, we identified systematic reviews of epidemiological studies, descriptive and analytical epidemiological investigations, and studies involving analysis of routine data.

RESULTS

Our searches identified a total of 5,843 potentially eligible studies, of which 49 satisfied our inclusion criteria. Of these, three were suitable for pooled estimates of prevalence. The incidence rates for all-cause anaphylaxis ranged from 1.5 to 7.9 per 100,000 person-years. These data indicated that an estimated 0.3% (95% CI 0.1-0.5) of the population experience anaphylaxis at some point in their lives. Food, drugs, stinging insects, and latex were the most commonly identified triggers.

CONCLUSIONS

Anaphylaxis is a common problem, affecting an estimated 1 in 300 of the European population at some time in their lives. Future research needs to focus on better understanding of the trends across Europe and identifying those most likely to experience fatal reactions.

Undernotification of anaphylaxis deaths in Brazil due to difficult coding under the ICD-10

BACKGROUND

Undernotification is well recognized as a key challenge to the study of anaphylaxis mortality, but it is seldom mentioned that one of its reasons is the difficult coding of the condition under the tenth revision of the international classification of diseases (ICD-10), given that there are no anaphylaxis-specific ICD-10, which are considered valid for coding underlying causes-of-death, and that official mortality statistics consider exclusively the underlying and disregard the contributing causes-of-death data recorded on death certificates. Brazilian mortality data were used as a case study to call attention to the inadequacy of the ICD-10 for the measurement of anaphylaxis deaths.

METHODS

Underlying and contributing causes-of-death data were used to estimate the rates of anaphylaxis deaths in the country over the years 2008-2010.

RESULTS

Of 498 anaphylaxis deaths were found, of which 75% were classified as 'definite' and 25% as 'possible anaphylaxis deaths'. The average national rate for these years was 0.87 per million per year. None of these deaths would have been found had we exclusively considered information from the underlying cause-of-death field.

CONCLUSION/RECOMMENDATIONS

The study of anaphylaxis mortality using secondary data requires the use of information derived from the underlying as well as from the contributing causes-of-death fields. Coding definitions should be standardized with a view of enabling trend analyses and international comparisons. The ICD-11 revision is a unique opportunity to improve the coding system so as to facilitate epidemiological studies of anaphylaxis mortality. Educational interventions targeted at improving the quality of death certificate completion are urgently needed.

Developing and testing search strategies to identify patients with active seasonal allergic rhinitis in general practice

AIM

We sought to assess the accuracy of different search terms to identify individuals with active seasonal allergic rhinitis (SAR) in general practice.

METHODS

A reference search strategy was developed to identify patients with active SAR. This was applied through inspection of electronic health records of patients aged 15-45 years in a 10% random sample of a general practice database. Searches used Read codes and medication relating to SAR. Sensitivity, specificity, and positive and negative predictive values were calculated.

RESULTS

Using the reference search strategy, 54/1092 (4.9%) of 15-45 year-old patients had current SAR. Searching for drugs used in nasal allergy had the highest sensitivity (85%) and good specificity (86%). Searching for a recorded history of SAR (H170) in the last two years was more specific (100%) but this approach only had limited sensitivity (17%).

CONCLUSIONS

Electronic searches can be used to identify patients with current SAR, but the accuracy varies widely. Larger numbers of sufferers can be identified using broader search parameters, but with increasing numbers of false positives. In contrast, more focused search strategies give a smaller yield needing less cleaning of data to identify true positives, but there is an associated increase in the number of false negatives.

Protocol for the adolescent hayfever trial: cluster randomised controlled trial of an educational intervention for healthcare professionals for the management of school-age children with hayfever

Background

Seasonal allergic rhinitis (hayfever) is common and can contribute to a considerable reduction in the quality of life of adolescents. This study aims to examine the effectiveness of standardised allergy training for healthcare professionals in improving disease-specific quality of life in adolescents with hayfever.

Methods/Design

Adolescents with a history of hayfever registered in general practices in Scotland and England were invited to participate in a cluster randomised controlled trial. The unit of randomisation is general practices.

The educational intervention for healthcare professionals consists of a short standardised educational course, which focuses on the management of allergic rhinitis. Patients in the intervention arm of this cluster randomised controlled trial will have a clinic appointment with their healthcare professional who has attended the training course. Patients in the control arm will have a clinic appointment with their healthcare professional and will receive usual care.

The primary outcome measure is the change in the Rhinoconjunctivitis Quality of Life Questionnaire with Standardised Activities (RQLQ(S)) score between baseline and six weeks post-intervention in the patient intervention and control groups.

Secondary outcome measures relate to healthcare professionals' understanding and confidence in managing allergic rhinitis, changes in clinical practice, numbers of consultations for hayfever and adolescent exam performance.

A minimum of 11 practices in each arm of the trial (10 patients per cluster) will provide at least 80% power to demonstrate a minimal clinically important difference of 0.5 in RQLQ(S) score at a significance level of 5% based on an Intraclass Correlation Coefficient (ICC) of 0.02.

Discussion

At the time of submission, 24 general practices have been recruited (12 in each arm of the trial) and the interventions have been delivered. Follow-up data collection is complete. 230 children consented to take part in the trial; however complete primary outcome data are only available for 160. Further recruitment of general practices and patients will therefore take place in the summer of 2010.

Trial Registration

Current Controlled Trials ISRCTN95538067

Epidemiology and disease burden from allergic disease in Scotland: analyses of national databases

BACKGROUND

There are ongoing concerns about the quality of care provided to patients with allergic disorders in Scotland, but there are relatively few reliable data on the overall disease burden. We sought to: (1) describe the incidence, prevalence and outcome of allergic disorders; (2) estimate healthcare burden and costs; and (3) investigate ethnic variations in the epidemiology and outcomes from allergic disorders in Scotland.

METHODS

DATA SOURCES

national surveys; primary care data; prescribing and medication data; hospital admissions data and mortality data.

RESULTS

Allergic disorders are extremely common in Scotland, affecting about one in three of the population at some time in their lives. Incidence was highest for eczema (10.2 per 1000 registered patients). Over 4% of all GP consultations and 1.5% of hospital admissions were for allergic disorders. There were 100 asthma deaths in 2005 (20 per million people). Direct healthcare costs for allergic disorders were an estimated pound130 million per year, the majority of these being incurred in primary care and related to asthma.

CONCLUSIONS

Allergic disorders are common in Scotland and given the very high proportion of children now affected, the high disease burden associated with these conditions is likely to persist for many decades.

Trends in the epidemiology and prescribing of medication for eczema in England

BACKGROUND

The prevalence of eczema, particularly in younger children, increased substantially over the second half of the 20th century. Analysis of primary healthcare data-sets offers the possibility to advance understanding about the changing epidemiology of eczema.

AIM

To investigate recent trends in the recorded incidence, lifetime prevalence, prescribing and consulting behaviour of patients with eczema in England.

METHODS

QRESEARCH is one of the world's largest national aggregated health databases containing the records of over nine million patients. We extracted data on all patients with a recorded diagnosis of eczema and calculated annual age-sex standardized incidence and lifetime period prevalence rates for each year from 2001-2005. We also analysed the consulting behaviour of these patients when compared with the rest of the QRESEARCH database population. The number of eczema prescriptions issued to people in England was also estimated.

RESULTS

The age-sex standardized incidence of eczema was 9.58 per 1000 person-years in 2001 and increased to 13.58 per 1000 patients in 2005 (p<0.001). By 2005, eczema affected an estimated 5,773,700 (95% confidence intervals [CI] 5,754,100-5,793,400) individuals in England, who, on average, consulted a general practitioner 4.02 (95% CI 4.01-4.03) times a year. During the study period, the number of eczema related prescriptions increased by 56.6% (95% CI 56.6-56.7), so by 2005 an estimated 13,690,300 (95% CI 13,643,200-13,737,600) prescriptions were issued.

CONCLUSIONS

Recorded incidence and lifetime prevalence of eczema in England continue to increase. Similar increases have also been observed in the estimated number of eczema prescriptions issued to the English population.

Incidence and prevalence of multiple allergic disorders recorded in a national primary care database

BACKGROUND

The co-existence of allergic conditions, food allergy, eczema, allergic rhinitis, asthma and anaphylaxis is thought to be increasing. Analysis of primary healthcare data-sets offers the possibility to advance understanding about the changing epidemiology of multiple allergic disorders.

AIM

To investigate recent trends in the recorded incidence, lifetime prevalence and consulting behaviour of patients with multiple allergic disorders in England.

METHODS

QRESEARCH is one of the world's largest national aggregated health databases containing the records of over nine million patients (including those who have left or died). Data were extracted on all patients with a recorded diagnosis of multiple allergic disorders, and annual age-sex standardized incidence and lifetime period prevalence rates were calculated for each year from 2001 to 2005. We also analysed the consulting behaviour of these patients when compared with the rest of the QRESEARCH database population.

RESULTS

The age-sex standardized incidence of multiple allergic disorders was 4.72 per 1000 person-years in 2001 and increased by 32.9% to 6.28 per 1000 patients in 2005 (p<0.001). Lifetime age-sex standardized prevalence of a recorded diagnosis of multiple allergic disorders increased by 48.9% from 31.00 per 1000 in 2001 to 46.16 in 2005 (p<0.001). Over this period, the mean consultation rate to general practitioners for these patients increased from 4.68 to 4.90 consultations per person per year.

CONCLUSIONS

Recorded incidence and lifetime prevalence of multiple allergic disorders in England have increased substantially in recent years.

Trends in the epidemiology and prescribing of medication for allergic rhinitis in England

OBJECTIVE

To investigate recent trends in the recorded incidence, lifetime prevalence and prescribing of symptom relief medication for allergic rhinitis in England.

DESIGN

Analysis of primary healthcare datasets.

SETTING

The UK prevalence of allergic rhinitis has increased very significantly over recent decades. Analysis of primary healthcare datasets offers the possibility to advance understanding about the changing epidemiology and management of allergic rhinitis. QRESEARCH is one of the world's largest national aggregated health databases containing the records of over nine million patients. We extracted data on all patients with a recorded diagnosis of allergic rhinitis and calculated annual age-sex standardized incidence and lifetime period prevalence rates for each year from 2001-2005. We also analysed prescribing trends for antihistamines and drugs used in nasal allergy in those with a recorded diagnosis of allergic rhinitis.

MAIN OUTCOME MEASURES

Age-sex standardized incidence, lifetime prevalence rates and prescribing trends for symptom relief medication for allergic rhinitis in England.

RESULTS

The age-sex standardized incidence of allergic rhinitis was 5.57 per 1000 person-years in 2001 and increased by 33.0% to 7.41 per 1000 person-years in 2005 (P<0.001). Lifetime age-sex standardized prevalence of a recorded diagnosis of allergic rhinitis increased by 43.2% from 46.35 per 1000 in 2001 to 66.37 per 1000 in 2005 (P<0.001). Over this period a 41.7% overall increase in prescriptions for antihistamines and drugs used in nasal allergy was observed (antihistamines 45.5%, drugs used in nasal allergies 35.5%).

CONCLUSIONS

Recorded incidence and lifetime prevalence of allergic rhinitis have increased substantially in recent years. A similar increase in prescriptions for antihistamines and drugs used in nasal allergy in patients with allergic rhinitis is also observed.

Trends in national incidence, lifetime prevalence and adrenaline prescribing for anaphylaxis in England

BACKGROUND

Analysis of primary healthcare datasets offers the possibility to increase understanding of the epidemiology of acute uncommon conditions such as anaphylaxis, but these datasets remain under-exploited.

AIM

To investigate recent trends in the recorded incidence, lifetime prevalence and prescribing of adrenaline for anaphylaxis in England.

METHODS

QRESEARCH is one of the world's largest national aggregated health databases containing the records of over nine million patients. We extracted data on all patients with a recorded diagnosis of anaphylaxis and calculated annual age-sex standardized incidence and lifetime period prevalence rates for each year from 2001-2005. We also analysed trends in adrenaline prescribing in those with a recorded diagnosis of anaphylaxis. National population figures were used to estimate numbers of people in England that have experienced anaphylaxis at some point in their lives.

RESULTS

The age-sex standardized incidence of anaphylaxis was 6.7 per 100,000 person-years in 2001 and increased by 19% to 7.9 in 2005. Lifetime age-sex standardized prevalence of a recorded diagnosis of anaphylaxis was 50.0 per 100,000 in 2001 and increased by 51% to 75.5 in 2005. Prescribing of adrenaline increased by 97% over this period. By the end of 2005 there were an estimated 37,800 people that had experienced anaphylaxis at some point in their lives.

CONCLUSIONS

Recorded incidence, lifetime prevalence and prescribing of adrenaline for anaphylaxis all showed substantial increases in recent years. An estimated 1 in 1,333 of the English population have at some point in their lives experienced anaphylaxis.

Will Systematized Nomenclature of Medicine-Clinical Terms improve our understanding of the disease burden posed by allergic disorders?

Analysis of data collected through the use of high-quality computerized systems is vital if we are to understand the health burden from allergic disease. Coding systems currently used, such as the World Health Organization's International Classification of Diseases and the Read system, have however been criticized as being unduly restrictive and hence inadequate for the detailed coding of allergic problems. Greater granularity of coding can be achieved by using the Systematized Nomenclature of Medicine-Clinical Terms (SNOMED-CT) system, which will be adopted by several countries including the United States and United Kingdom. Before the introduction of SNOMED-CT, it is important that several issues are resolved, including ensuring that adequate mapping occurs from existing systems, that the SNOMED-CT is trialled before general implementation, and that training is provided for users new to coding as part of their clinical practice. Of particular importance is that the allergy fraternity bring to light any gaps in allergy coding through the creation of a working group to advise the newly formed International Healthcare Terminology Standards Development Organisation. There is also a role for allergy experts, working in conjunction with government agencies and professional bodies, to determine a recommended set of codes, which will obviate some of the inevitable challenges raised by a very fluid coding structure for those wishing to undertake secondary analysis of health care datasets.

Comparison of international guidelines for the emergency medical management of anaphylaxis

BACKGROUND

Guideline-based treatment approaches for managing anaphylaxis are widely believed to result in good outcomes, but the strength of evidence underpinning the recommendations made therein is unclear.

OBJECTIVE

To identify and compare national guidelines for the emergency medical management of anaphylaxis and to describe the extent to which the evidence base in support of key recommendations is made clear.

METHODS

We systematically searched key medical databases and contacted the World Allergy Organization and anaphylaxis charities in several countries to identify national guidelines. Full text copies of relevant papers were obtained and, where necessary, translated. Data were abstracted onto a customized data extraction sheet; this process was independently checked by a second reviewer.

RESULTS

Guidelines originating from Australia, Canada, Russia, UK, Ukraine and the USA were identified. While these were in agreement on the broad principles of management, there were important variations in relation to the treatments to be used and the dose and route of administration of these preparations. Most guidelines failed to make clear the strength of evidence underpinning the recommendations being made.

CONCLUSIONS

There are important international differences in the recommended emergency management of anaphylaxis. It is important that an agreed core evidence-based guideline for the management of anaphylaxis is now developed, which can then be adapted for national/local use. Clinicians need to be aware of the limitations of existing guidelines.