Menckeberg Tanja T, Belitser Svetlana V, Bouvy Marcel L, Bracke Madelon, Lammers Jan-Willem J, Raaijmakers Jan A M, Leufkens Hubert G M
Division of Pharmacoepidemiology & Pharmacotherapy, Utrecht Institute for Pharmaceutical Sciences, Utrecht, The Netherlands.
BMC Health Serv Res. 2007 Jul 10;7:106. doi: 10.1186/1472-6963-7-106.
In order to accurately distinguish gaps of varying length in drug treatment for chronic conditions from discontinuation without resuming therapy, short-term observation does not suffice. Thus, the use of inhalation corticosteroids (ICS) in the long-term, during a ten-year period is investigated. To describe medication use as a continuum, taking into account the timeliness and consistency of refilling, a Markov model is proposed.
Patients, that filled at least one prescription in 1993, were selected from the PHARMO medical record linkage system (RLS) containing >95% prescription dispensings per patient originating from community pharmacy records of 6 medium-sized cities in the Netherlands.The probabilities of continuous use, the refilling of at least one ICS prescription in each year of follow-up, and medication free periods were assessed by Markov analysis. Stratified analysis according to new use was performed.
The transition probabilities of the refilling of at least one ICS prescription in the subsequent year of follow-up, were assessed for each year of follow-up and for the total study period.The change of transition probabilities in time was evaluated, e.g. the probability of continuing ICS use of starters in the first two years (51%) of follow-up increased to more than 70% in the following years. The probabilities of different patterns of medication use were assessed: continuous use (7.7%), cumulative medication gaps (1-8 years 69.1%) and discontinuing (23.2%) during ten-year follow-up for new users. New users had lower probability of continuous use (7.7%) and more variability in ICS refill patterns than previous users (56%).
In addition to well-established methods in epidemiology to ascertain compliance and persistence, a Markov model could be useful to further specify the variety of possible patterns of medication use within the continuum of adherence. This Markov model describes variation in behaviour and patterns of ICS use and could also be useful to investigate continuous use of other drugs applied in chronic diseases.
为了准确区分慢性病药物治疗中不同时长的用药中断与不再继续治疗的停药情况，短期观察并不足够。因此，对吸入性糖皮质激素（ICS）在十年期间的长期使用情况进行了调查。为了将药物使用描述为一个连续过程，同时考虑到续方的及时性和一致性，提出了一个马尔可夫模型。
从PHARMO医疗记录链接系统（RLS）中选取了在1993年至少开具过一张处方的患者，该系统包含来自荷兰6个中等城市社区药房记录的每位患者>95%的处方配药情况。通过马尔可夫分析评估连续使用的概率、随访各年中至少开具一张ICS处方的续方概率以及停药期。根据新使用者情况进行了分层分析。
对随访各年以及整个研究期间，评估了随访次年至少开具一张ICS处方的续方转移概率。评估了转移概率随时间的变化，例如，新使用者在随访的前两年（51%）继续使用ICS的概率在随后几年增加到70%以上。评估了十年随访期间不同用药模式的概率：新使用者连续使用（7.7%）、累积用药中断（1 - 8年，69.1%）和停药（23.2%）。新使用者连续使用的概率较低（7.7%），且ICS续方模式比既往使用者（56%）更具变异性。
除了流行病学中确定依从性和持续性的既定方法外，马尔可夫模型可能有助于进一步明确依从性连续过程中各种可能的用药模式。这个马尔可夫模型描述了ICS使用行为和模式的变化，也可能有助于研究慢性病中其他药物的连续使用情况。
