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Impact of the introduction of mandatory generic substitution in South Africa: private sector sales of generic and originator medicines for chronic diseases
Author(s) -
Gray Andrew Lofts,
SantaAnaTellez Yared,
J Wirtz Veronika
Publication year - 2016
Publication title -
tropical medicine and international health
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.056
H-Index - 114
eISSN - 1365-3156
pISSN - 1360-2276
DOI - 10.1111/tmi.12785
Subject(s) - medicine , population , pharmacoepidemiology , pharmacology , environmental health , medical prescription
Objective To assess the impact of mandatory offer of generic substitution, introduced in South Africa in May 2003, on private sector sales of generic and originator medicines for chronic diseases. Methods Private sector sales data (June 2001 to May 2005) were obtained from IMS Health for proton pump inhibitors ( PPI s; ATC code A02 BC ), HMG ‐CoA reductase inhibitors (statins; C10 AA ), dihydropyridine calcium antagonists (C08 CA ), angiotensin‐converting enzyme inhibitors ( ACE ‐I; C09 AA ) and selective serotonin reuptake inhibitors ( SSRI s; N06 AB ). Monthly sales were expressed as defined daily doses per 1000 insured population per month ( DDD / TIM ). Interrupted time‐series models were used to estimate the changes in slope and level of medicines use after the policy change. ARIMA models were used to correct for autocorrelation and stationarity. Results Only the SSRI s saw a significant rise in level of generic utilisation (0.2 DDD / TIM ; P < 0.001) and a fall in originator usage (−0.1 DDD / TIM ; P < 0.001) after the policy change. Utilisation of generic PPI s fell (level 0.06 DDD / TIM , P = 0.048; slope 0.01 DDD / TIM , P = 0.043), but utilisation of originator products also grew (level 0.05 DDD / TIM , P < 0.001; slope 0.003, P = 0.001). Generic calcium antagonists and ACE ‐I showed an increase in slope (0.01 DDD / TIM , P = 0.016; 0.02 DDD / TIM , P < 0.001), while the originators showed a decrease in slope (‐0.003 DDD / TIM , P = 0.046; −0.01 DDD / TIM , P < 0.001). There were insufficient data on generic statin use before the policy change to allow for analysis. Conclusion The mandatory offer of generic substitution appeared to have had a quantifiable effect on utilisation patterns in the 2 years after May 2003. Managed care interventions that were already in place before the intervention may have blunted the extent of the changes seen in this period. Generic policies are an important enabling provision for cost‐containment efforts. However, decisions taken outside of official policy may anticipate or differ from that policy, with important consequences.