Comparison of adherence measures using claims data in the South African private health sector.

BACKGROUND: Medication adherence measurement is becoming increasingly important. Biological assays and markers, directly observed therapy, self-reports, pill counts and surveys have been successfully used to assess adherence under various circumstances, but may be limited by cost, ethical concerns and self-reported bias. Administrative claims data, in addition to offering a solution to these limitations, provide access to large study populations under real clinical practice situations, and in a timely and effective manner. With the wide range of adherence measures determined from claims data available - some of which have been found to be mathematically equivalent - researchers are often faced with the decision of choosing which is appropriate. An assessment of the various measures is therefore important for better understanding and to facilitate future adherence studies using administrative data. OBJECTIVES: To compare different adherence measures using data from a medicines claims database in South Africa (SA), employing montelukast for the purpose of illustration. METHODS: This retrospective, cross-sectional research used data from 1 January 2006 to 31 December 2015 from a privately owned pharmaceutical benefits management (PBM) company in SA. Claims for montelukast were identified and adherence was determined using the continuous multiple-interval measure of oversupply (CMOS), compliance ratio (CR), modified medication possession ratio (MPRm), refill compliance rate (RCR), continuous single-interval measure of medication acquisition (CSA) and proportion of days covered (PDC) capped at 1. The measures were compared with the medication possession ratio (MPR) as the reference. RESULTS: The MPR, CMOS and CR were equivalent, each yielding an adherence value of 86%. The MPRm, RCR and average CSA yielded higher adherence values of 96.9%, 117.2% and 129.0%, respectively, whereas the PDC produced a lower adherence value of 76.0%. The measures that used the entire study period as the denominator produced consistent results compared with the measures that used the difference between claims dates as denominator. CONCLUSIONS: The MPR is considered the most widely used metric to measure adherence using administrative data, but it may not always be applicable owing to the type of data available. Adherence computed using the CR, CMOS and PDC capped was found to be comparable to the MPR, and they may therefore be used as alternatives.

Identification of potential drug-drug interactions between antiretroviral drugs from prescriptions in the private health-care sector in South Africa.

The aim of this study was to identify potential drug-drug interactions (DDIs) between antiretroviral drugs (ARVs) and to determine whether prescribed daily doses (PDDs) from prescriptions can be used in the evaluation of these interactions. A quantitative, retrospective drug utilization study was performed on 49,995 and 81,096 ARV prescriptions from a South African pharmacy benefit management company, which were prescribed to 7664 and 10,162 HIV patients for 2005 and 2006, respectively. Potential DDIs identified across different age groups were 778 for 2005 and 1155 for 2006; the majority occurred in patients aged 19 to ≤45 years. The potential DDIs identified between ARVs were all interacting at clinical significance level 2 according to guidelines indicated by Tatro. These results demonstrate that potential DDIs were identified between ARVs mostly in three ARV combinations: Kaletra(®) (lopinavir/ritonavir) and efavirenz, lopinavir/ritonavir and nevirapine and combinations of indinavir and ritonavir. There is a need for more education on the prescribing protocols for ARVs in the treatment of HIV-infected patients in the private health-care sector in South Africa.

Further Potential Savings Attributable to Maximum Generic Substitution of Antidepressants in South Africa: a Retrospective Analysis of Medical Claims

The main objective of the study was to calculate potential cost savings that could have been generated by maximum generic substitution of antidepressants within the private health care sector of South Africa from 2004 to 2006. Data on computerized medicine claims of patients receiving one or more antidepressants during three consecutive years (i.e. 2004; 2005 and 2006) were elicited from a South African pharmaceutical benefit management company. The total study population consisted of 292 071 items (N = 5 982 869) on 273 673 prescriptions (N = 5 213 765) at a total cost of R56 183 697.91 (N = R1 346 210 929.00). A quantitative; retrospective drug utilization review was conducted; and data were analyzed using the Statistical Analysis Systemr programme. Potential cost savings were computed for criteria-eligible substances in the study population. Generic medicine constituted 58.7(N = 292 071) of all antidepressants claimed; at a total cost of 28.2(N = R1 346 210 929.00) of all incurred costs. With total substitution of the average price of all criteria-eligible innovators; a potential saving of 9.3(N = R56 183 697.91) of the actual antidepressant cost over the study period was calculated. In developing countries with limited health care resources; generic medicines can be cost-saving treatment alternatives

Prescribing patterns of medicine classified as 'antidepressants' in South African children and adolescents

The main objective of this study was to characterise prescribing patterns of medicine classified as 'antidepressants' (hereafter simply referred to as antidepressants) in children and adolescents in the private health care sector of South Africa. A retrospective drug utilisation design was used to identify patients aged 19 years and younger from a South African pharmaceutical benefit management company's database; whom were issued at least one antidepressant between 1 January 2006 and 31 December 2006. Prescribed daily dosages (PDDs) were calculated using the Statistical Analysis Systemr program. A total of 1 013 patients received a mean number of 2.88 (SD 3.04) prescriptions per patient. Females received more prescriptions than their male counterparts; with the highest prevalence in the 15 = 19 years age group. The pharmacological groups most prescribed were the selective serotonin reuptake inhibitors (43.0) and the tricyclics (42.7); with imipramine (22.04) and amitriptyline (19) as the most commonly prescribed drugs. Approximately 30(n = 2 300) of all antidepressants in the study population were prescribed off-label. Amitriptyline and clomipramine were prescribed at daily dosages higher than recommended in children and adolescents aged 9 = 15 years. Lithium; trimipramine; trazodone and sulpiride were prescribed at sub-therapeutic dosages in adolescents. This study provided insight in the prescribing patterns of medicine classified as antidepressants in South African children and adolescents. These drugs; however; have many indications. Further research is needed to determine reasons why specific drugs are prescribed in this population

Prevalence of possible drug-drug interactions between antiretroviral agents in different age groups in a section of the private health care sector setting in South Africa.

BACKGROUND: The chronic nature of human immunodeficiency virus (HIV) infection requires lifelong highly active antiretroviral (ARV) therapy (HAART) to continuously suppress HIV-1 viral replication, thus reducing morbidity and mortality. HAART is restricted by complex dosing, drug-drug interactions (DDIs) and toxicities. OBJECTIVE: To determine the prevalence of possible DDIs between ARV drugs in different age groups in a section of the private primary health care sector in South Africa. METHODS: A quantitative, retrospective drug utilization review was performed on 47 085 ARV prescriptions claimed through a national medicine claims database during 2006. Possible DDIs identified were classified according to a clinical significance rating as described by Tatro [Drug Interaction Facts 2005. St Louis, MO: Facts and Comparisons (2005)]. RESULTS: The total number of patients who received prescriptions that were claimed through the medicine claims database was 275 424, of whom 25.11% were males, 28.28% were females and the gender of 46.61% patients was unknown. Of the total number of patients, 3.27% were HIV patients of which an average of 5.23 +/- 3.86 ARV prescriptions (n = 47 085) per patient were claimed for representing 4.73% of the total number of prescriptions claimed during the study period (N = 993 804). HIV patients received an average of 2.36 +/- 0.61 ARVs per prescription. Only 4.95% of the prescriptions had one ARV medicine item, 56.04% two, 37.10% three, 1.75% four and <1% had more than four. Of 960 DDIs identified, 1.88% were for patients < or =6 years, 4.27% for patients >6 years and < or =12 years, 0.63% for patients >12 and < or =19 years, 32.40% for patients <19 years and < or =40 years, 60.21% for patients <40 years and < or =60 years and 0.63% for patients >60 years with patients <40 years and < or =60 years having the highest number of DDIs and patients older than 60 years the lowest. The majority of DDIs between the ARVs presented in significance levels 2 and 4. The most important interactions were between: indinavir (IDV) and ritonavir (n = 199); efavirenz (EFV) and lopinavir/ritonavir (n = 65) and EFV and IDV (n = 60) all interacting at level 2. CONCLUSION: The importance of using drug utilization study as an identification tool to provide insight into the prescribing and utilization patterns of ARV drugs, to provide optimal therapy for patients infected with HIV is emphasized.

Prevalence of drug-drug interactions of antiretroviral agents in the private health care sector in South Africa.

OBJECTIVES: Human immunodeficiency virus (HIV) infection can be effectively treated with highly active antiretroviral therapy (HAART), requiring concomitant administration of three to four different agents, often with a high potential for drug-drug interactions (DDIs). This study aimed to determine the prevalence of possible DDIs between antiretrovirals (ARVs) themselves and other drugs. DESIGN: Retrospective drug utilisation study using data from a national medicine claims database for the period 1 January to 31 December 2004. SETTING: A section of the private health care sector in South Africa. SUBJECTS: All ARV prescriptions (N=43 482) claimed during 2004. The possible DDIs found were classified according to a clinical significance rating described by Tatro (2005) in his book Drug Interaction Facts. RESULTS: A total of 5 305 882 medicine items were prescribed; of these, 1.92% (N=101 938) were ARVs. Of the total number of 2 595 254 prescriptions, 1.68% (N=43 482) contained ARVs. A total number of 18 035 DDIs (81 different types) were identified; of these, 83.89% (N=15 130) were DDIs between ARVs and other drugs, while 16.11% (N=2 905) were DDIs between ARVs themselves. Possible DDIs with a clinical significance level of 1 (major, N=17) and 2 (moderate, N=1 436) represented 8.06% (N=1 453) of the total number of identified interactions. CONCLUSIONS: Since concomitant use of ARVs and other drugs used to treat HIV complications is increasing, there is a need to understand and anticipate these DDIs and to overcome them by dose adjustments and patient education, so that they are not life threatening to HIV/AIDS patients.

Prevalence of Drug-Drug Interactions of Antiretroviral Agents in the Private Health Care Sector in South Africa

Human immunodefiency virus (HIV) infection can be effectively treated with highly active antiretroviral therapy (HAART); requiring concomitant administration of three to four different agents; often with a high potential for drug-drug interactions (DDIs). This study aimed to determine the prevalence of possible DDIs between antiretrovirals (ARVs) themselves and other drugs. Design. Retrospective drug-utilisation study using data from from a national medicine claims database for the period 1 January to 31 December 2004. Setting. A section of the private healthcare sector in South Africa. Subjects. All ARV prescriptions (N=43482) claimed during 2004. The possible DDIs found were classified according to a clinical significant rating as described by Tatro7 (2005) in his book; Drug Interactions Facts and comparisons. Results. A total of 5305882 medicine items were prescribed; of these; 1.92(N=101 938) accounted for ARVs. Of the total number of 2595254 prescriptions; 1.68(N=43 482); were ARVs. A total number of 18035 DDIs (81 different types) were identified; of these; 83.89; (n=15130) were DDIs between ARVs and other drugs; while 16.11(n=2905) were DDIs between ARVs themselves. Possible DDIs with a clinical significance level of 1 (major; n=17) and 2 (moderate; n=1436) represented 8.06(n=1 453) of the total number of identified interactions. Conclusions. Since concomitant use of ARVs and other drugs used to treat HIV complications is increasing; there is a great need of understanding and anticipating these DDIs; overcoming them by dose adjustments and patient education by pharmacists; so that they are not life threatening to HIV/AIDS patients

Investigation into the Prescribing Patterns and Cost of Antidiabetic Medicine in South Africa

"The general objective of this study was to investigate the prescribing patterns and cost of antidiabetic medicine in the private health care sector in South Africa by using a medicine claims database. A quantitative; retrospective drug utilisation study was performed on data for the year 2004. Oral antidiabetic medicine accounted for 81 (n =143 447) and 39 (R29 734 360.61) respectively of the total prevalence and cost of all antidiabetic products prescribed. Metformin was the most frequently prescribed oral antidiabetic medicine; with an average cost of R58.42 (SD = 31.78). The three most frequently prescribed classes of insulin (insulin lispro; soluble insulin and isophane; and soluble insulin aspartame and protamine) together accounted for 63 of all the insulin prescribed; and 67 of the total cost of prescribed insulin. Almost 39 (n = 62 717) of the ""combination therapy"" prescriptions were for a sulfonylurea in combination with a biguanide plus at least one other antidiabetic product. A trend towards combination therapy away from monotherapy was observed. Prescribed Daily Doses (PDDs) calculated for oral antidiabetic medicines were more or less in line with recommended treatment guidelines. Drug utilisation review studies thus provide valuable insight into the treatment of diabetes - indicating areas of possible over- and under usage; providing decision-makers with critical information to curb unnecessary costs."

Prescribing Patterns of Antiretroviral Drugs in a Section of Private Health Care Sector of South

The general objective of this study was to investigate the prescribing patterns and cost of antiretroviral (ARV) drugs in the private health care sector in South Africa by using a medicine claims database. A quantitative; retrospective drug utilisation review was performed on data retrieved from 2001; 2002 and 2004 records. Antiretroviral drugs repre- sented 0.38 (n = 1 475 380) for 2001; 0.72 (n = 2 076 236) for 2002; and 1.68 (n = 2 595 254) for 2004 of all studied prescriptions. The total cost of the ARV drugs represen-ted 1.31 (R379 708 489) for 2001; 3.03 (R601 350 325) for 2002; and increased to 5.25 (R661 223 146) for 2004 of all drugs claimed. All ARV medicine items claimed during 2001 (n = 9 796) and 2002 (n = 35 271) were innovator products. Only 5.23 (n=5 329) of all the ARV medicine items (n = 101 938) claimed during 2004 were generic products. The average cost per ARV medicine item for 2004 increased from R317.93 (SD = R190.80) for the period January to April to R369.20 (SD = R219.50) for the period May to August; and decreased to R324.79 (SD = R212.48) for the period September to December and resulted in a cost saving of R41 044.35 for the period May to August versus September to December. Both the prevalence and cost of ARV drug therapy increased from 2001 to 2002. The prevalence increased from 2002 to 2004; but the cost decreased during 2004. The decrease in the cost of ARV drug therapy is probably a result of the implementation of the new pricing regulations in May 2004