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Table 2 Impact of price adjustments on monthly utilization of ACEIs, ARBs and overall renin-angiotensin drugs

From: Impact of drug price adjustments on utilization of and expenditures on angiotensin-converting enzyme inhibitors and angiotensin receptor blockers in Taiwan

Dependent variables

Time period

Factored ARIMA model*

Independent variables†

Coefficients‡

p value

Primary analyses

ACEIs

Jan 1997 to

Dec 2008

p = (6);

Constant

232,380

<0.0001

  

q = (6)(12)

Baseline trend

5,531

<0.0001

   

PA2000 level change

-48,286

<0.0001

   

PA2004 level change

28,987

0.0073

   

PA2004 trend change

-4,860

<0.0001

   

PA2006 trend change

-3,529

0.0002

   

CNY

-36,256

<0.0001

ARB

Feb 1998 to Dec 2008

p = (2,3)(12)

Baseline trend

5,044

<0.0001

   

PA2003 trend change

5,014

<0.0001

   

PA2007 trend change

8,583

0.0003

   

CNY

-21,476

0.0219

Renin-angiotensin drugs

Jan 1997 to Dec 2008

p = (2,5)(12)

Constant

135,289

<0.0001

   

Baseline trend

12,027

<0.0001

   

PA2000 level change

-73,794

0.0053

   

CNY

-32,789

0.0371

Subgroup analyses for ACEIs

Patented ACEIs

Jan 1997 to Dec 2008

p = (6);

Constant

18,039

<0.0001

  

q = (6)

Baseline trend

872

<0.0001

   

PA2000 level change

-9,466

<0.0001

   

PA2001 level change

6,416

0.0022

   

PA2004 trend change

1,235

<0.0001

   

PA2005 level change

-13,602

<0.0001

   

CNY

-7,318

<0.0001

Off-patent ACEIs

Jan 1997 to Dec 2008

p = (12);

Constant

209,374

<0.0001

  

q = (9)

Baseline trend

4,617

<0.0001

   

PA2000 level change

-37,219

<0.0001

   

PA2004 level change

26,145

0.0028

   

PA2004 trend change

-5,201

<0.0001

   

PA2006 trend change

-4,593

<0.0001

   

CNY

-20,665

0.0021

Off-patent original branded ACEIs

Jan 1997 to Dec2008

p = (1,4,5)(12)

Constant

179,478

<0.0001

   

Baseline trend

527

0.0081

   

PA2000 level change

-21,380

0.0031

   

PA2004 trend change

-2,574

<0.0001

   

CNY

-11,501

0.0003

Off-patent generic ACEIs

Jan 1997 to Dec 2008

p = (12);

Constant

25,416

<0.0001

  

q = (12)

Baseline trend

4,205

<0.0001

   

PA2000 level change

-23,138

<0.0001

   

PA2004 level change

22,925

<0.0001

   

PA2005 trend change

-4,315

<0.0001

   

PA2006 trend change

-3,197

<0.0001

   

CNY

-9,447

0.0445

  1. *Factored ARIMA model is represented by p, d, q: p, auto-regressive order; d, differencing order; q, moving-average order; seasonal order is represented by p = (12), d = (12) or q = (12). Take ACEIs as an example. The moving-average operator represented by q = (6)(12) means
  2. (1-θ 6 B 6 ) (1-θ 12 B 12 ).
  3. †Parsimonious models were adopted, and therefore, only significant independent variables were incorporated into the model.
  4. ‡The unit of the regression coefficient is defined daily dose (DDD).
  5. ACEIs, angiotensin-converting enzyme inhibitors; ARBs, angiotensin receptor blocker; ARIMA, auto-regressive integrated moving-average;
  6. CNY, Chinese new year; PA2000, price adjustment implemented on April 1, 2000; PA2001, price adjustment implemented on April 1, 2001; PA2003, price adjustment implemented on March 1, 2003; PA2004, price adjustment implemented on November 1, 2004; PA2005, price adjustment implemented on September 1, 2005; PA2006, price adjustment implemented on November 1, 2006; PA2007, price adjustment implemented on September 1, 2007.
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BMC Public Health

ISSN: 1471-2458

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