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WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT
• Under-reporting of adverse drug reactions to regulatory authorities is common, and there is concern about falling numbers of general practitioner reports.
• Although previous work has suggested high prescribers are less interested in pharmacovigilance, a recent examination of reporting to the Yellow Card scheme has suggested ADR reporting is correlated with high prescribing rates.
• This study aimed to examine influences on the reporting of ADRs to the Yellow Card scheme in primary care.
• High prescribing rates within primary care are correlated with low ADR reporting rates.
• Several Primary Care Trust characteristics related to general practitioners, such as increased proportions of single-handed general practitioners and larger list sizes, are associated with low ADR reporting rates.
AIM(S) To examine Primary Care Trust (PCT) demographics influencing general practitioner (GP) involvement in pharmacovigilance.
METHODS PCT adverse drug reaction (ADR) reports to the Yellow Card scheme between April 2004 and March 2006 were obtained for the UK West Midlands region. Reports were analysed by all drugs, and most commonly reported drugs (‘top drugs’). PCT data, adjusted for population size, were aggregated. Prescribing statistics and other characteristics were obtained for each PCT, and associations between these characteristics and ADR reporting rates were examined.
RESULTS During 2004–06, 1175 reports were received from PCTs. Two hundred and eighty (24%) of these reports were for 14 ‘top drugs’. The mean rate of reporting for PCTs was 213 reports per million population. A total of 153 million items were prescribed during 2004–06, of which 33% were ‘top drugs’. Reports for all drugs and ‘top drugs’ were inversely correlated with the number of prescriptions issued per thousand population (rs=−0.413, 95% CI −0.673, −0.062, P < 0.05, and r=−0.420, 95% CI −0.678, −0.071, P < 0.05, respectively). Reporting was significantly negatively correlated with the percentages of male GPs within a PCT, GPs over 55 years of age, single-handed GPs within a PCT, the average list size of a GP within a PCT, the overall deprivation scores and average QOF total points. ADR reports did not correlate significantly with the proportion of the population over 65 years old.
CONCLUSIONS Some PCT characteristics appear to be associated with low levels of ADR reporting. The association of low prescribing areas with high ADR reporting rates replicates previous findings.
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Spontaneous reports of suspected adverse drug reactions (ADRs) are an important source of pharmacovigilance data [1, 2]. However, there is widespread under-reporting of adverse drug reactions (ADRs) . In the UK, the House of Commons Committee of Public Accounts , a National Audit Office report , an independent review of the Yellow Card scheme , a House of Commons Health Committee  and the British Medical Association  have all noted concerns about falling numbers of ADRs reported to the Yellow Card scheme.
The Yellow Card scheme solicits reports of novel, serious, or medically significant ADRs to established medicines, and reports of all reactions to medicines under intensive surveillance (indicated with a black triangle [▾]). These are most commonly newly marketed products. Historically, general practitioners (GPs) have submitted more reports than any other reporter group, but there has been a marked decline in the number of GP reports: in the West Midlands region of the United Kingdom the number of reports from GPs fell by 58% between 1994 and 2005.
The West Midlands Centre for Adverse Drug Reactions, in its role as Yellow Card Centre West Midlands (YCCWM), acts as a regional outreach centre of the Medicines and Healthcare products Regulatory Agency (MHRA), which administers the Yellow Card scheme jointly with the Commission on Human Medicines. Until April 2006, this centre also processed Yellow Cards reports from within the West Midlands region.
We wished to examine the association of various Primary Care Trust (PCT) characteristics on reporting rates to the Yellow Card Scheme within the West Midlands Strategic Health Authority (SHA).
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During the period 2004–06, 1175 Yellow Card reports were submitted within the West Midlands region from PCTs. The mean rate of reporting was 213 reports per million population (SD 101.28, median 208, range 58–553). There were 14 reports of death associated with ADRs. The top drugs list (consisting of 14 drugs) for 2004–06 is presented in Table 1. These drugs accounted for 24% of the total number of reports received. Thirteen of the 14 ‘top drugs’ were black triangle [▾] drugs. Therefore, the reporting rate for ‘top drugs’ can be considered a marker for the reporting of reactions to black triangle drugs.
Table 1. Combined ADR reports for ‘top drugs’ for 2004–06
|Drug name||Number of reports|
Altogether 153 050 187 prescriptions were issued in the West Midlands during 2004–06; the list of top drugs accounted for 5 007 259 prescriptions (3.3%).
The PCT population measured in 2004 was significantly correlated with the number of reports for all drugs (square root transformation, r= 0.815, 95% CI 0.644, 0.908, P < 0.001) and ‘top drugs’ (square root transformation r= 0.644, 95% CI 0.369, 0.185, P < 0.001). We therefore used an ADR reporting rate normalized per million population. PCT characteristics are listed in Table 2.
Table 2. West Midlands Primary Care Trust characteristics related to general practice
|PCT characteristic||Mean (SD)||Range|
|Percentage of male GPs||65.7% (5.9%)||54.2–75.4%|
|Percentage of single-handed practices||26.0% (17.2%)||0–58.8%|
|Percentage of GPs over 55 years of age*||22.8% (median 22.2%)||8–50%|
|Average list size||1699 (177)||1349–2035|
|Total QOF points||1013 (22)||972–1044|
|Proportion of population over 65 years of age*||16.3% (median 16.8%)||9.8–19.9%|
|Index of multiple deprivation score*||24 (median 19.7)||10.8–52.2|
Reports for all drugs (Figure 1A) and ‘top drugs’ per million population (Figure 1B) correlated negatively with the number of prescriptions issued for all drugs per thousand population (Table 3). The square of the correlation coefficient (r2) was 0.18 for ‘top drugs’ per million population, suggesting that the prescribing rate was responsible for 18% of the variability in the ADR reporting rate.
Figure 1. ADR reports per million population vs. number of prescriptions per thousand population in the West Midlands during the financial years 2004–05 and 2005–06. A) ADR reports per million population for all drugs and prescriptions per thousand population for all drugs (rs=−0.413, P < 0.05). B) ADR reports per million population (square root + 2 transform) for ‘top drugs’ and prescription per thousand population for ‘top drugs’ with fitted line (r= -0.420, P (two-tailed) < 0.05, r2= 0.18)
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Table 3. Correlates between ADR reporting rates and PCT variables
|PCT variable||ADR reports per million population*||ADR reports per million population (square root +2 transform) for ‘top drugs’|
|Prescriptions per thousand population||rs=−0.413, P < 0.05 95% CI −0.673, −0.062||r=−0.420, P < 0.05 95% CI −0.678, −0.071|
|Percentage of male GPs within PCT||rs=−0.482, P < 0.01 95% CI −0.717, −0.147||r=−0.50, P < 0.01 95% CI −0.729, −0.171|
|Percentage of single handed practitioners||rs=−0.734, P < 0.001 95% CI −0.865, −0.508||r=−0.663, P < 0.001 95% CI −0.826, −0.398|
|Average list size||rs=−0.519, P= 0.003 95% CI −0.741, −0.196||r=−0.434, P < 0.05 95% CI −0.687, −0.088|
|Proportion of GPs over 55 years of age (square root transform)||rs=−0.566, P < 0.01 95% CI −0.769, −0.258||r=−0.485, P < 0.01 95% CI −0.720, −0.151|
|Average total QOF points||rs= 0.484, P < 0.01 95% CI 0.150, 0.719||r= 0.491, P < 0.01 95% CI 0.158, 0.723|
|Overall deprivation score*||rs=−0.550, P < 0.01 95% CI −0.760, −0.236||rs=−0.570, P < 0.01 95% CI −0.769, −0.258|
|Proportion of population over 65 years of age*||rs= 0.147, P= 0.438 95% CI −0.225, 0.482||rs= 0.128, P= 0.502 95% CI −0.244, 0.466|
Reporting of ADRs to all drugs and ‘top drugs’ per million population correlated negatively with the percentage of male GPs within a PCT, the percentage of GPs over 55 years of age, the percentage of single-handed GPs within a PCT and the average list size of a GP within a PCT (Table 3). The proportion of single-handed GPs was significantly associated with list size (r= 0.726, 95% CI 0.495, 0.861, P < 0.001).
Reporting of ADRs to all drugs and ‘top drugs’ per million population was correlated with average QOF total points. PCTs with a higher proportion of single-handed GPs had a significantly lower average QOF performance (r=−0.758, 95% CI −0.879, −0.548, P < 0.001).
No statistically significant correlation was found between the proportion of the PCT population over 65 years of age and the number of reports per million population for all drugs (rs= 0.147, 95% CI −0.225, 0.482, P= 0.438) or ‘top drugs’ (rs= 0.128, 95% CI −0.244, 0.466, P= 0.502).
Overall deprivation scores correlated negatively with reporting rate per million population for all drugs (rs=−0.550, 95% CI −0.760, −0.236, P < 0.01) and ‘top drugs’ (rs=−0.570, 95% CI −0.769, −0.258, P < 0.01). This relationship held when the health component of the deprivation index was analysed independently for all drugs (rs=−0.542, 95% CI −0.755, −0.226, P < 0.01) and ‘top drugs’ (rs=−0.598, 95% CI −0.768, −0.303, P < 0.001). Higher deprivation scores were significantly associated with increased list size (rs= 0.523, 95% CI 0.201, 0.744, P= 0.003); however, they correlated strongly with increases in the proportion of the single-handed GPs (rs= 0.777, 95% CI 0.578, 0.888, P < 0.001).