Page last updated: 25-MAR-2008

General Practice - Practice Team Information (PTI)

Comparison of QOF and PTI rates for the QOF clinical domains

Until recently PTI has been the main source of national prevalence estimates from primary care in Scotland. With the introduction of the new General Medical Services (nGMS) contract in 2004, data from the Quality and Outcomes Framework (QOF) provide a potential additional source. PTI and QOF were developed for different purposes and measure slightly different things. Both are useful in their own right but we would not expect prevalence estimates to be the same. Therefore a number of points should be noted before making comparisons between PTI and QOF based estimates of prevalence for a given condition:

  • PTI reflects active disease problems. It is based on a count of those who consult because of a specific diagnosis during a specified year. For people with a particular problem, a consultation for a different health problem will not be included in statistics for that problem. For example, someone with high blood pressure (hypertension) who has a consultation that is only about backache will be counted as having a backache consultation, but not as having a hypertension consultation.
  • QOF prevalence is based on inclusion on a practice's disease register. Because of its focus on secondary prevention, each register usually includes all those who have ever had a diagnosis of a condition, even if it is not currently an active problem. For example, all those with previous coronary heart disease (CHD) are included on the CHD register for a practice, even if the problem occurred some time ago and they are currently well.
  • QOF indicators were developed for quality improvement rather than for epidemiological purposes. For example, QOF excludes people with asthma who are not currently on medication, so that effort is focused on those most likely to benefit from review. PTI, by contrast, provides an estimate of all those with a current diagnosis of asthma where they have consulted for it at least once over the year.
  • Because QOF data is provided in aggregated form, it is not easy to adjust for age, gender or other factors in order to allow comparisons.
  • Because QOF data is provided in aggregated form it is not possible to estimate how many people have more than one chronic condition (that is, have co-morbidities). This is feasible with PTI data.
  • PTI has an established programme of audit and quality control. NHS Boards have verification programmes but as yet little information on the quality of QOF data has been published.


QOF covers a limited range of chronic diseases that account for only around 23% of contacts within general practice. PTI provides information on all diagnoses, and for consultations where no clear diagnosis is made. Other issues related to specific conditions are discussed below.

Notes on specific conditions

Asthma
Because of the need to focus on those most likely to benefit from intensive monitoring, the QOF asthma registers exclude patients who have had no prescription for asthma drugs during the last twelve months. Such patients may still have a diagnosis of asthma, but may have minimal symptoms not requiring treatment. PTI statistics would include such patients if the reason for consultation was stated to be asthma and the PTI definition may therefore better reflect the true prevalence of asthma.

Atrial Fibrillation - new 2006/07
The QOF register for atrial fibrillation (AF) includes all those who currently have a clinical diagnosis of AF, including those who have paroxysmal (intermittent) AF. PTI figures will only include those who consult specifically because of AF, and are therefore likely to be much lower.

Cancer
QOF excludes people with cancer where the diagnosis was made before 1st April 2003. PTI does not have the facility to select on this criterion and relies on a cancer diagnosis being recorded for a primary care contact during the year, whereas much cancer treatment takes place in the secondary care setting. For cancer prevalence and incidence in Scotland more useful statistics are available elsewhere on  ISD's cancer information pages.

CHD
The QOF register includes people who have ever had coronary revascularisation, myocardial infarction (heart attack) or other CHD diagnoses, even if they do not have a current active diagnosis of CHD. PTI statistics include such patients only if the reason for a consultation was stated to be CHD and only if they consulted for CHD in the year of analysis. In previous years, Left Ventricular Dysfunction (LVD) was a subset of CHD, but patients with heart failure as a result of LVD are now also included in heart failure registers.

Chronic Kidney Disease (CKD) - new 2006/07
The QOF indicator requires a register of people, aged over 18, with stages 3-5 of the disease, based on their estimated Glomerular Filtration rate (eGFR). It is very unlikely that this will be recorded as the main reason for consultation within PTI statistics, and PTI data are not likely to be suitable to measure the prevalence of this condition.

COPD
The QOF rules do not allow patients to be on both asthma and COPD registers, while PTI allows people with both diagnoses to be included in estimates for both diseases. This is likely to affect only a small number of cases. It is generally accepted that some patients with COPD have reversible airways obstruction. The QOF rules do not allow these patients to be included on the COPD register, but PTI statistics include such patients if the reason for consultation was stated to be COPD. This might have the effect of making the QOF an underestimate of COPD prevalence compared to PTI.

Dementia - new 2006/07
The QOF indicator definition applies to all people diagnosed with dementia either directly by the GP or through referral to secondary care. PTI figures will include only those consultations where dementia was specifically recorded as the reason for consultation.

Depression - new 2006/07
The QOF indicator relates specifically to patients who are already on the diabetes or CHD registers. It would be difficult to produce a corresponding figure from PTI data and comparisons are unlikely to be feasible.

Diabetes - definition revised 2006/07 (defined by narrower range of Read Codes now - those codes specific to Type 1 or Type 2)
The QOF rules exclude people aged less than 17 years and those with gestational (pregnancy) diabetes. QOF guidance assumes that a review will be carried out annually. PTI statistics reflect those who consult for a condition. If reviews are carried out less frequently than once a year, the number included in PTI data will be smaller than those who are on the QOF register because of these not having attended for review within the year. Additionally, diabetes prevalence rates from QOF use the whole practice population as the denominator but include only those aged 17 and over in the numerator. This will lead to an underestimate of total prevalence.

Epilepsy - definition revised 2006/07
QOF rules restrict the epilepsy register to those currently on treatment. PTI includes those who consult because of epilepsy even if they are not on epilepsy drugs, though this is likely to be a fairly small number of people. QOF rules exclude those under 18 years of age. Epilepsy prevalence from QOF uses the whole population as the denominator but includes only those aged  18 or over in the numerator, which will lead to an underestimate of prevalence.

Heart Failure - new 2006/07
The QOF heart failure indicator is defined so that Left Ventricular Dysfunction is now included whether or not CHD has also been diagnosed. As with other conditions, PTI prevalence estimates would be based only on consultations specifically for heart failure, so might be expected to underestimate prevalence compared to the QOF.

Hypertension
The QOF rules include guidance about defining hypertension. PTI statistics record hypertension based only on the judgement of the member of the practice team seeing the patient.

Hypothyroidism
The QOF rules exclude patients from the register if they are not taking thyroxine, while PTI includes all patients consulting the practice team because of a diagnosis of hypothyroidism. This difference is unlikely to be important in practice, as patients with hypothyroidism would generally be expected to be receiving thyroid replacement therapy.

Learning Disabilities - new 2006/07
The QOF register includes people aged 18 and over who have learning disabilities. PTI data reflect current active problems and such patients would be included in statistics only if the reason for consultation was specifically stated to be their learning disability.

Mental health - definition revised 2006/07
The criteria for inclusion on QOF mental health registers depend on a clinical judgment about the nature of the problem and cannot easily be equated to a particular list of diagnoses. This makes it difficult to compare PTI and QOF estimates of the frequency of mental health problems.  Since April 2006, the QOF definition has included only patients with serious mental illness (defined as schizophrenia, bipolar affective disorder or other psychoses). Previously, QOF relied upon a more generalised set of mental health conditions and also only included patients who required, and had consented to, regular follow-up.

Obesity - new 2006/07
This new QOF indicator includes all people aged 16 years and over with a BMI of at least 30. PTI consultations will record ?obesity? where it is the reason for consultation, but do not necessary use a consistent BMI definition of this term. As a result, direct comparison of QOF and PTI figures would not be appropriate.

Palliative Care - new 2006/07
The QOF register for palliative care includes all people aged 18 years and over in need of palliative or supportive care.  Comparable figures are not available from PTI data.

Conditions assessed for smoking - new 2006/07
This new QOF indicator relates to the smoking status of people with particular chronic conditions (coronary heart disease, stroke or TIA, hypertension, diabetes, COPD or asthma). As PTI data are based on reasons for consultation, a direct comparison would not be possible.

Stroke and Transient Ischaemic Attack (TIA)
The QOF register includes people who have ever had a stroke or TIA. PTI statistics reflect current active problems and include such patients only if the reason for consultation was stated to be stroke or TIA.

 

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Related information:

QOF Clinical Domain areas - contacts as percentage of total contacts
Co-morbidities of CHD, diabetes and hypertension

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