Usage Patterns and Cost Analysis of Antihypertensive Drugs Reimbursed by the National Health Insurance in Gabon
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Usage patterns and cost analysis of antihypertensive drugs reimbursed by the national health insurance in Gabon ML Akebayeri orcid.org/ 0000-0001-6044-3047 BPharm Dissertation submitted in fulfillment of the requirements for the degree Master of Pharmacy in Pharmacy Practice at the Potchefstroom Campus of the North-West University Supervisor: Prof JR Burger Co-supervisor: Prof MS Lubbe Assistant supervisor Mrs M Cockeran Graduation May 2018 Student number: 22034773 ACKNOWLEDGEMENTS Thank you Lord Almighty, for helping me to complete this work. My gratitude goes to the following persons at the North-West University for their contributions and support through the compiling of this dissertation: My supervisor, Prof JR Burger and co-supervisor Prof MS Lubbe for their support, patience and guidance through this work. Mrs M Cockeran for the statistics consultation services and Prof JR Burger for her support. Mrs E Oosthuizen for her technical assistance. Mrs A Van der Spoel from International office of NWU and Ms T Joubert for all the administrative support. Mrs A Pretorius from the Natural Sciences Library of NWU for assisting me with the reference list of this work. To the entire staff of the Department of Pharmacy Practice at the NWU for your support since the first year of my BPharm degree. My appreciation and thanks also go to the following people: Dr Itou-y-Maganga, for your approval to conduct the research at your premises and for the collection and capturing of the data as well as your personal support. Mrs V Viljoen for proofreading and upgrading the grammatical use of the language. Dr B Mbadinga for your support and friendship through this work. i DEDICATION I dedicate this work to my late grandfather, Dr Alexandre N Awassi, my parents Alain and Sophie, my brothers and sisters, Loic, Alexandre, Letissia, Simonie, Andrix, Richard, Kevin and Aime, for granting me all the financial and emotional support I needed. You have made a significant impact in my life. ii ABSTRACT Background: The ‘Caisse Nationale d’Assurance Maladie et de Garantie Sociale’ (CNAMGS), the national health insurance fund was implemented since 2007, so that every Gabonese citizen has access to quality healthcare. Currently, in Gabon, little has been done regarding a drug utilisation review and its impact on drug cost and prescribing patterns. Objective: The study aimed to review the usage patterns, and analyse the cost of antihypertensive drugs reimbursed by the CNAMGS fund. Methods: A retrospective drug utilisation review was conducted over a 12-month period (1 June 2013 – 31 May 2014) on prescription claims data, obtained from a community pharmacy in Gabon. The study population consisted of all prescriptions (N = 51 838) containing one or more antihypertensive drugs received at the pharmacy during the period of study. Information on the prescriptions and on the costs of drugs were then reported on a data capturing form and analysed using SPSS for Windows (SPSS IBM Corp., 2013). The defined daily dose (DDD), DDDs/1000 inhabitants/day and cost/DDD were used as drug utilisation metrics. Antihypertensive drugs were classified as plain formulation for those with a single active ingredient and as fixed-dose combinations for those with two or more active substances in a single drug. Drug cost was given in Central African CFA francs (ISO 4217 code: XAF). Results: 2 504 (1.2%) prescriptions for 1 586 patients containing 3 360 antihypertensive drugs were analysed. The majority of hypertensive patients were females (n = 1 097; 69.2%). The mean patient age was 56.53 ± 14.77 years (95% CI 55.80 - 57.26), and the majority of patients (51.4%) were between the ages 45 to 65 years old. Most antihypertensives were prescribed by general practitioners (n = 1108, 44.2%) and specialists (n = 1 049, 41.9%) (p < 0.0001, Cramér’s V = 0.42). Plain formulations were mostly prescribed (61.7%) as compared to fixed-dose combinations (38.3%). Calcium channel blockers were the most frequently prescribed plain formulations (22.2%), followed by diuretics and potassium sparing agents (15.4%), angiotensin converting enzyme inhibitors (8.6%), beta-blockers (6.7%), central acting agents (4.0%) and angiotensin receptor blockers (3.0%). Generic equivalents represented only 6.8% (n = 228) of all antihypertensives claimed. Antihypertensives were prescribed at 8.35 DDDs/1000 inhabitants/day for plain formulations and 4.90 DDDs/1000 inhabitants/day for fixed-dose combinations. The total cost of antihypertensive drugs amounted to 46 576 511 XAF, of which 27 217 870 XAF (58.4%) was reimbursed by iii CNAMGS and the remaining 19 358 641 XAF (41.6%) was the patients’ co-payments. The total cost of generic equivalents amounted to 2 117 003 XAF (4.6% of the total cost). The mean cost for a prescription for an antihypertensive drug reimbursed by CNAMGS was 10 870 ± 7 617 XAF (95% CI, 10 571 – 11 168); in which angiotensin receptor blockers appeared to be the most expensive (cost/DDD = 476.9). Diuretics and beta-blockers as plain formulations had the lowest cost/DDD ratios, at 199.8 and 191.7, respectively. These drugs were, therefore, less expensive than other antihypertensives in the study, such as angiotensin converting enzyme inhibitors (cost/DDD = 302.9), angiotensin receptor blockers (cost/DDD = 476.9), calcium channel blockers (cost/DDD = 301.8), central acting agents (cost/DDD = 315.9) and even fixed-dose combinations (cost/DDD = 439.3). It was deducted that generic substitution of captopril and amlodipine could have led to a potential saving of 0.9% and 4.5% of the total cost of angiotensin converting enzyme inhibitors and calcium channel blockers, respectively. The overall substitution where generic equivalents were available could have led to a potential saving of 4.8%, the total cost of all antihypertensives claimed during the period of study (2 246 594 XAF), or 1 313 009 XAF would have been saved by CNAMGS. Conclusion and recommendations: Diuretics as first-line therapy are less expensive for the treatment of hypertension. The CNAMGS fund has the potential to decrease medicine cost through promotion of generic prescribing and dispensing. Key terms: Caisse Nationale d’Assurance Maladie et de Garantie Sociale (CNAMGS), Gabon, antihypertensive drugs, Defined daily dose (DDD), DDD/1000 inhabitants/day, cost/DDD, drug utilisation review, generic substitution iv UITTREKSEL Agtergrond: Die "Caisse Nationale d'Assurance Maladie et de Garantie Sociale" (CNAMGS), die nasionale gesondheidsversekeringfonds is sedert 2007 geïmplementeer, sodat elke inwoner van Gaboen tot kwaliteit gesondheidsorg toegang het. Tans is daar weinig in Gaboen gedoen met betrekking tot medisyneverbruiksevaluering en die impak daarvan op geneesmiddelkoste en voorskryfpatrone. Doelwit: Die studie het ten doel om die verbruikspatrone te evalueer en die koste van antihipertensiewe middels wat deur die CNAMGS fonds vergoed word, te ontleed. Metodes: 'n Retrospektiewe medisyneverbruiksevaluering is uitgevoer op voorskrif-eisedata, van 'n 12-maande tydperk (1 Junie 2013 tot 31 Mei 2014), verkry uit 'n gemeenskapsapteek in Gaboen. Die studiepopulasie het bestaan uit alle voorskrifte (N = 51 838) wat een of meer antihipertensiewe geneesmiddels bevat, wat gedurende die studietydperk by die apteek ingedien is. Voorskrifinligting en geneesmiddelkoste is met behulp van 'n data-opname-vorm versamel en met behulp van ”SPSS for Windows” program (SPSS IBM Corp., 2013) ontleed. Die gedefinieerde daaglikse dosis (DDD), DDD/1000 inwoners/dag en koste/DDD is gebruik as medisyneverbruiksmaatstawwe. Antihipertensiewe middels met 'n enkele aktiewe bestanddeel is geklassifiseer as eenvoudige formulerings en dié met twee of meer aktiewe bestanddele in 'n enkele produk as ʼn vaste dosis kombinasie. Geneesmiddelkoste is gegee in Sentraal-Afrikaanse CFA-frank (ISO 4217-kode: XAF). Resultate: 'n Totaal van 2 504 (1.2%) voorskrifte vir 1 586 pasiënte wat 3 360 antihipertensiewe middels bevat het, is ontleed. Die meerderheid hipertensiewe pasiënte was vroue (n = 1 097; 69.2%). Die gemiddelde ouderdom van pasiënte was 56.53 ± 14.77 jaar (95% VI, 55.80 – 57.26), en die meeste pasiënte (51.4%) was tussen die ouderdomme 45 tot 65 jaar oud. Die meerderheid antihipertensiewe middels is deur algemene praktisyns (n = 1108, 44.2%) en spesialiste voorgeskryf (n = 1 049, 41.9%) (p < 0.0001, Cramér's V = 0.42). Eenvoudige formulerings is die meeste voorgeskryf (61.7%) in vergelyking met vaste dosis kombinasies (38.3%). Kalsiumkanaalblokkeerders was die mees voorgeskrewe eenvoudige formulerings (22.2%), gevolg deur diuretika en kaliumsparende middels (15.4%), angiotensien- omskakelingsensiem-inhibeerders (8.6%), beta-blokkeerders (6.7%), sentraalwerkende middels (4.0%), en angiotensien-reseptoreblokkeerders (3.0%). Generiese ekwivalente het slegs 6.8% (n = 228) van alle antihipertensiewe middels wat geëis was, verteenwoordig. Antihipertensiewe middels is voorgeskryf teen 8.35 DDDs/1000 inwoners/dag vir eenvoudige formulerings en 4.90 DDDs/1000 inwoners/dag vir vaste dosis kombinasies. Die totale koste van v antihipertensiewe middels het 46 576 511 Sentraal-Afrikaanse franke CFA XAF beloop, waarin 27 217 870 XAF (58.4%) deur CNAMGS vergoed is en die oorblywende 19 358 641 XAF (41.6%) bybetalings van die pasiënte was. Die totale koste van generiese ekwivalente het 2 117 003 XAF (4.6% van die totale koste) beloop. Die gemiddelde koste van 'n voorskrif vir antihipertensiewe middels wat deur CNAMGS terugbetaal is, was 10 870 ± 7 617 XAF (95% VI, 10 571 – 11 168);