Antibiotic Prescribing and Use

Two million antibiotic prescriptions were billed to Blue Cross Blue Shield of Michigan (BCBSM) in 2009; more were likely dispensed that cost less than the co-payment. The BCBSM data show that members are prescribed just under one (.9) antibiotic per year. This is comparable to the national average of .88 prescriptions per person.2

Overall antibiotic prescribing for adult BCBSM members decreased 9.3 percent between 2007 and 2009, from .96 prescriptions per member to .87 prescriptions per member.

FIGURE IB6:1 Antibiotic Prescribing Rate, Adults, BCBSM, 2007–2009

	2007	2008	2009
Prescriptions per 1000 Members	959	922	870

Many of the CDC-initiated outreach activities aimed at reducing inappropriate antibiotic use have been focused on pediatricians.3 Despite these efforts, antibiotic prescribing rates for BCBSM children increased 4.5 percent between 2007 and 2009. The overall increase in antibiotic use combined with data presented later in this issue brief indicates that there continues to be too high a rate of inappropriate use.

FIGURE IB6:2 Antibiotic Prescribing Rate, Children, BCBSM, 2007–2009

	2007	2008	2009
Prescriptions per 1000 Members	930	905	972

The National Committee for Quality Assurance (NCQA) has identified a list of “antibiotics of concern.” These antibiotics are called “broad spectrum” antibiotics, meaning they are effective against a wide range of bacteria. While these drugs can be very valuable in treating infections that have not responded to other agents or were caused by multiple types of bacteria, in many cases an infection can be more precisely targeted with a narrow spectrum antibiotic. Since the use of any antibiotic agent can promote resistance to that agent, broad spectrum antibiotics should be reserved for the most serious infections. Overuse of these agents is of concern because it can cause increased resistance to them, leaving even fewer drugs available to treat serious infections.4

In 2009, 49.1 percent of antibiotic prescriptions in the overall BCBSM population were for these broad spectrum antibiotics. This compares to a national rate of 47 percent.5 6 Between 2007 and 2009, the percent of antibiotic prescriptions for antibiotics of concern stayed nearly steady in the adult BCBSM population, decreasing 0.4 percent during that time period. In the same time period, the percentage of antibiotics of concern prescribed to BCBSM children increased 3.4 percent, going from 44.9 percent to 46.4 percent. One possible explanation for this increase in children is the continuing rise in resistant pathogens that are responsible for ear infections in children, necessitating broad spectrum antibiotic treatment.7Other possible reasons are that children get different infections than adults, and that some drugs that are used in adults are not used for pediatric patients.

FIGURE IB6:3 Percent of Antibiotic Prescriptions for Antibiotics of Concern, 2007–2009

	2007	2008	2009
Adults	50.3%	51.2%	50.1%
Children	44.9%	45.3%	46.4%

When antibiotic prescribing is indicated, determining which antibiotic to prescribe is influenced by several factors. The most important factor should be which antibiotic is most effective against the bacteria likely to be responsible for a given infection. However, factors such as physician and patient preference, convenience, and familiarity with specific drugs often play a role.

Figure 4 shows the top antibiotics prescribed for BCBSM adults in 2009, highlighting those categorized by the NCQA as “antibiotics of concern.” Five of the top ten most common antibiotics are classified as “antibiotics of concern.” Azithromycin (also known as Zithromax or Z-Pak) is the most frequently prescribed antibiotic for adults, making up 20 percent of all antibiotic prescriptions.

FIGURE IB6:4 Top Antibiotic Drugs, Adults, BCBSM, 2009

Product Name	BCBSM Total Spending in 2009	Number of Prescriptions	Price per Course
Azithromycin (Zithromax)	$4,234,950.16	292,797	$14.46
Amoxicillin (Amoxil)	$920,529.32	184,921	$4.98
Cephalexin Monohydrate (Keflex)	$577,347.89	113,861	$5.07
Ciprofloxacin Hydrochloride (Cipro)	$392,565.25	107,295	$3.66
Amoxicillin-Clavulanate (Augmentin)	$2,131,969.68	88,257	$24.16
Sulfamethoxazole-Trimethoprim DS (Bactrim DS)	$384,944.21	87,423	$4.40
Doxycycline Hyclate (Vibramycin)	$532,470.62	75,536	$7.05
Levofloxacin (Levaquin)	$6,566,226.78	59,525	$110.31
Clindamycin Hydrochloride (Cleocin)	$498,133.18	53,473	$9.32
Penicillin V Potassium (Pen-V)	$246,756.42	42,614	$5.79

The most commonly prescribed antibiotic for children in 2009 was Amoxicillin. Only three of the top ten antibiotics are categorized as “antibiotics of concern.”

FIGURE IB6:5 Top Antibiotic Drugs, Children, BCBSM, 2009

Product Name	BCBSM Total Spending in 2009	Number of Prescriptions	Price per Course
Amoxicillin (Amoxil)	$926,714.58	161,776	$5.73
Azithromycin (Zithromax, Z-Pak)	$2,484,634.61	129,401	$19.20
Amoxicillin-Clavulanate (Augmentin)	$1,312,709.55	51,664	$25.41
Cefdinir (Omnicef)	$2,307,757.13	41,695	$55.35
Cephalexin Monohydrate (Keflex)	$262,568.84	35,070	$7.49
Sulfamethoxazole-Trimethoprim (Bactrim)	$156,157.36	17,221	$9.07
Minocycline Hydrochloride (Minocin)	$303,914.09	15,159	$20.05
Sulfamethoxazole-Trimethoprim DS (Bactrim DS)	$43,602.15	9,753	$4.47
Doxycycline Hyclate (Vibramycin)	$49,590.39	9,401	$5.28
Penicillin V Potassium (Pen-V)	$33,660.58	7,467	$4.51

In general, we know antibiotic prescribing8 varies widely across regions, health plans, and even individual physicians.9 In Michigan, antibiotic prescribing rates among the BCBSM population vary across hospital service areas (HSA). These differences cannot be explained by different rates of illness alone.10

In the adult population in 2009, the highest overall antibiotic prescribing rate in Michigan was 2.2 times the lowest antibiotic prescription rate. Eleven HSAs had prescribing rates that were at least 30 percent higher than the state average: Cheboygan, Gaylord, Grosse Point, Hillsdale, L’anse, Ludington, Marlette, Pigeon, Sturgis, Watervliet, and West Branch. Five HSAs had prescribing rates 25 percent or less than the state average: Ann Arbor, Chelsea, Greenville, Saline, and Southfield.

FIGURE IB6:6: Antibiotic Prescribing for Adults, BCBSM, 2009

Prescribing for the pediatric population showed much higher variation than prescribing for the adult population. In 2009, the rate of antibiotic prescribing for BCBSM children varied by a factor of 4.6, from .54 antibiotics per member in Ann Arbor to 2.2 antibiotics per member in Dowagiac. Thirty-six HSAs had rates more than 30 percent above the state average, while nine had rates at least 25 percent below the state average. Eight of the nine low utilizing HSAs were in Southeast Michigan. High utilizing HSAs were clustered in the Upper Peninsula, in Northern Lower Michigan, and on the Ohio border.

Southeast Michigan has a lower rate of antibiotic use in children and more pediatricians per 1000 population than outstate Michigan. Though there is not a statistically significant association between lower antibiotic use rates and higher numbers of pediatricians per 1000 population at the HSA level, it may account, at least in part, for differences that can be seen between southeast Michigan and the rest of the state.

FIGURE IB6:7: Antibiotic Prescribing for Children, BCBSM, 2009

FIGURE IB6:8 Antibiotic Prescribing Rates and Appropriate Use Measures, BCBSM, 2009

HSA	Total antibiotics prescribed per 1000 people	Antibiotics prescribed per 1000 children	Percent of children with upper respiratory infections given antibiotics	Percent of children with pharangytis given appropriate testing	Antibiotics prescribed per 1000 adults	Percent of adults with bronchitis prescribed antibiotics
Dowagiac	1370	2205	48.9%	44.2%	1070	n/a
Pigeon	1337	1936	42.3%	n/a	1176	n/a
Hillsdale	1331	1607	19.3%	50.0%	1231	86.0%
Gaylord	1331	1897	40.0%	55.8%	1165	84.9%
Sturgis	1298	1689	49.2%	38.7%	1168	n/a
Cheboygan	1265	1569	19.8%	60.8%	1178	85.7%
Marlette	1253	1324	33.3%	n/a	1230	n/a
Watervliet	1252	1576	32.1%	54.7%	1140	74.2%
Bad Axe	1249	1815	47.0%	11.0%	1044	87.9%
West Branch	1223	1584	62.3%	37.8%	1139	81.3%
Niles	1218	1544	25.7%	68.5%	1108	83.0%
L’anse	1199	1389	25.0%	30.8%	1135	70.8%
Coldwater	1196	1533	28.6%	37.7%	1074	76.4%
Ludington	1184	1227	20.7%	38.6%	1171	87.4%
Gladwin	1176	1845	42.4%	37.3%	1006	n/a
Newberry	1172	1473	38.2%	n/a	1092	84.6%
Adrian	1163	1570	31.3%	45.4%	1035	80.2%
Iron River	1161	1382	n/a	n/a	1113	n/a
Petoskey	1160	1404	23.7%	76.1%	1083	82.3%
Cadillac	1148	1341	25.2%	34.4%	1081	75.0%
Grosse Pointe	1146	1184	16.3%	60.8%	1131	77.4%
Manistee	1140	1250	12.1%	30.1%	1108	78.2%
Clare	1138	1591	27.2%	53.1%	997	80.7%
Standish	1131	1501	46.6%	27.3%	1024	62.2%
Reed City	1128	1377	26.2%	54.9%	1053	n/a
St. Joseph	1122	1634	28.6%	60.4%	956	78.4%
Iron Mountain	1116	1308	24.4%	38.8%	1052	n/a
Sandusky	1108	1318	51.9%	46.2%	1042	n/a
Mount Pleasant	1108	1351	15.6%	41.7%	1018	66.9%
Sault Ste Marie	1092	1185	13.5%	38.7%	1062	71.6%
Laurium	1090	1168	24.6%	36.2%	1062	n/a
Grayling	1089	1354	29.5%	46.8%	1031	82.1%
Caro	1085	1133	22.7%	37.0%	1071	77.8%
Manistique	1079	1162	22.8%	31.4%	1055	n/a
Alma	1075	1319	35.6%	47.9%	990	76.1%
Escanaba	1072	1306	32.6%	38.9%	994	72.4%
Berrien Center	1069	1607	n/a	n/a	862	n/a
Rochester	1064	1148	17.9%	68.6%	1035	70.3%
Ontonagon	1062	1195	n/a	n/a	1025	n/a
Flint	1062	1148	27.3%	46.4%	1036	83.1%
Paw Paw	1056	1334	16.7%	68.6%	953	84.8%
Harbor Beach	1056	1584	43.6%	n/a	872	n/a
Pontiac	1051	1204	26.7%	50.3%	1001	78.5%
Cass City	1047	1151	22.7%	n/a	1014	n/a
Albion	1045	1087	29.7%	50.0%	1033	n/a
Tawas City	1044	1384	38.4%	40.0%	973	76.8%
Deckerville	1033	1300	n/a	n/a	947	n/a
Ishpeming	1025	1229	40.8%	52.4%	957	n/a
Big Rapids	1024	1364	24.6%	47.2%	921	80.8%
Bay City	1023	1156	20.6%	58.7%	984	72.0%
Tecumseh	1018	1165	26.3%	36.1%	968	89.3%
Port Huron	1018	1140	21.5%	58.8%	974	78.0%
Milford	1002	1088	21.8%	64.8%	972	79.3%
Carson City	1002	1035	45.5%	45.7%	991	n/a
Ironwood	999	1136	n/a	n/a	965	n/a
Troy	996	1080	17.6%	64.5%	968	74.0%
Alpena	993	1196	35.3%	18.0%	933	78.3%
Monroe	991	1078	33.3%	61.7%	964	81.0%
Royal Oak	988	1002	14.6%	70.8%	983	74.6%
Crystal Falls	985	1339	n/a	n/a	900	n/a
Hastings	981	1229	21.0%	50.3%	889	81.3%
St. Johns	980	1211	37.5%	65.5%	895	74.7%
Mount Clemens	979	1108	20.6%	61.5%	933	74.2%
Traverse City	974	1082	17.1%	51.4%	937	72.3%
Saginaw	963	1068	21.4%	49.9%	931	76.3%
Hancock	963	1011	18.3%	45.6%	944	n/a
Owosso	963	1250	31.3%	60.3%	871	80.4%
Charlevoix	947	1111	28.0%	64.2%	891	77.6%
Kalamazoo	938	1051	13.7%	62.9%	900	81.4%
Marshall	931	988	36.8%	52.6%	910	83.7%
Jackson	930	1108	25.8%	74.6%	867	81.1%
Three Rivers	930	1031	22.2%	51.2%	896	n/a
South Haven	922	1140	50.0%	60.5%	853	83.6%
Munising	913	1190	n/a	n/a	840	n/a
Lapeer	905	1038	32.7%	41.9%	862	81.4%
St. Clair	885	1045	17.3%	40.0%	836	75.8%
Lakeview	874	1150	n/a	n/a	793	n/a
Warren	873	928	17.4%	57.6%	854	75.4%
Battle Creek	872	853	15.3%	63.3%	878	77.2%
Farmington Hills	863	851	16.4%	59.4%	867	73.4%
Lansing	852	987	22.8%	60.6%	808	79.4%
Frankfort	844	790	n/a	n/a	857	n/a
Midland	838	992	16.8%	51.8%	785	77.7%
Marquette	831	939	23.1%	56.4%	802	78.2%
Charlotte	831	945	46.6%	46.0%	791	76.5%
Trenton	822	851	31.0%	46.8%	812	72.4%
Garden City	821	922	27.1%	42.3%	784	82.3%
Howell	814	786	18.2%	60.3%	828	80.3%
Livonia	806	803	18.7%	50.4%	806	78.7%
Zeeland	798	976	n/a	n/a	703	n/a
Wyandotte	796	811	27.9%	45.0%	791	77.3%
Dearborn	789	842	22.0%	37.4%	770	77.3%
Ionia	780	965	n/a	40.9%	714	n/a
Northport	778	789	n/a	n/a	776	n/a
Holland	765	824	10.6%	68.2%	742	78.5%
Grand Rapids	759	853	16.8%	67.4%	722	74.3%
Allegan	744	765	18.9%	69.0%	736	n/a
Taylor	739	665	26.5%	43.7%	763	82.6%
Grand Haven	732	771	8.2%	66.7%	717	80.5%
Madison Heights	728	724	22.0%	59.0%	729	66.2%
Fremont	727	781	17.8%	48.1%	707	66.7%
Detroit	712	575	16.1%	43.0%	756	69.4%
Wayne	687	633	25.0%	40.2%	704	77.7%
Muskegon	679	711	14.0%	52.7%	668	79.0%
Greenville	658	785	26.9%	60.6%	610	n/a
Chelsea	644	695	14.9%	70.6%	624	67.9%
Southfield	583	518	15.4%	63.8%	602	74.3%
Ann Arbor	553	483	15.7%	63.4%	583	77.0%
Saline	538	494	13.9%	62.1%	558	76.0%
TOTAL	896	972	21.9%	54.9%	870	77.7%

Prescribing antibiotics for viral infections, which do not respond to antibiotics and nearly always get better on their own, is a driver of overall antibiotic prescribing rates. One study found that antibiotic prescribing for colds, upper respiratory infections, and bronchitis accounts for nearly one third of antibiotics prescribed in the outpatient setting.11

To quantify the extent to which inappropriate antibiotic prescribing drives variation in overall prescribing rates, we examined the association between measures of appropriate prescribing and overall prescription rates. Our measures of appropriate prescribing are based on measures used in the Healthcare Effectiveness Data and Information Set (HEDIS), a tool used by health plans to measure the effectiveness of healthcare.12

The first measure is the percentage of children with upper respiratory infections (URI) that are given antibiotics. Upper respiratory infections involve the nose, sinuses, throat, and trachea, with the most common example being the common cold. Overall in 2009, 21.9 percent of BCBSM covered children diagnosed with URI were prescribed antibiotics. This percentage excludes children who were prescribed antibiotics for reasons other than the URI, such as ear infections or strep throat. This rate is a decrease from the 44 percent of children who received antibiotics for URIs found in a national study in 1992, but there is still substantial room for improvement, since antibiotics are not found to improve outcomes in URIs in children.

There is a correlation between the percentage of children given antibiotics for URIs and the overall pediatric antibiotic prescribing rate in a geographic region. Figure 9 shows the relationship between those two measures. Regions with a higher overall antibiotic use rate for children also had a higher percentage of antibiotics used for conditions with a viral diagnosis. Of the variation in overall pediatric antibiotic prescribing rates, 31.4 percent is related to variation in prescribing rates for URI. In other words, it appears that high use regions of the state have a higher use, at least in part, due to a higher inappropriate use of antibiotics.

FIGURE IB6:9: Percent of Children Prescribed Antibiotics for Upper Respiratory Infection by Pediatric Prescribing Rate, BCBSM, 2009

Another measure of appropriateness in antibiotic prescribing for children is whether children who received antibiotics for pharyngitis (sore throat) also received a test to confirm the infection was bacterial. Overall, 56.3 percent of children received the appropriate test when given antibiotics for a sore throat. Appropriate testing for pharangytis is related to overall antibiotic prescribing. That is, places with high rates of testing to confirm bacterial infection also had lower rates of antibiotic prescribing. This relationship is shown in Figure 10. Of the overall variation in pediatric antibiotic prescribing, 12.1 percent is related to testing patterns for pharyngitis. Regions of the state with higher use of antibiotics were also regions with lower rates of testing for the presence of bacterial infection.

FIGURE IB6:10: Percent of Children with Pharyngitis Given Appropriate Testing by Pediatric Prescribing Rate, BCBSM, 2009

For adults, a measure of appropriateness was the percentage of adults diagnosed with bronchitis who were not given antibiotics. Like URI, most cases of bronchitis are viral and improve with appropriate non-antibiotic treatment. Prescribing rates for BCBSM adults with bronchitis in 2009 were very high—77.2 percent received a prescription for antibiotics. Although rates were high throughout the state, there was a statistically significant correlation between the rates of prescribing antibiotics for bronchitis and those regions with high overall use rates. That is, regions with the highest antibiotic dispensing for bronchitis also had the highest antibiotic dispensing overall. Of the variation in overall use rates, 8.8 percent is related to prescribing antibiotics for bronchitis (Figure 11).

FIGURE IB6:11: Percent of Adults Prescribed Antibiotics for Bronchitis by Adult Prescribing Rate, BCBSM, 2009

Efforts to educate providers and patients, especially for pediatric providers and patients, have resulted in overall decreased use of antibiotics for viral infections. High rates of inappropriate antibiotic prescribing occur in some parts of Michigan, particularly outside of southeast Michigan. Of particular concern are the lack of testing for presence of a bacterial infection in children prior to prescribing an antibiotic, the continuing high use rates of antibiotics for viral infections in both children and adults, and the relatively high use of broad spectrum antibiotics among the adult population.

A number of efforts in Michigan have focused on reducing the inappropriate use of antibiotics. Most notably, the Michigan Antibiotic Resistance Reduction Coalition has had a number of successes in reducing inappropriate use over time. Overuse of antibiotics continues to be a major health problem in Michigan and nationally. Further efforts to reduce inappropriate use are essential for safeguarding our health and preserving the effectiveness of antibiotics.