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  • Research note
  • Open Access

Use of power-law analysis to predict abuse or diversion of prescribed medications: proof-of-concept mathematical exploration

  • 1Email author,
  • 2,
  • 3,
  • 4 and
  • 1
BMC Research Notes201811:523

https://doi.org/10.1186/s13104-018-3632-y

  • Received: 8 June 2018
  • Accepted: 20 July 2018
  • Published:

Abstract

Objective

To conduct a proof-of-concept study comparing Lorenz-curve analysis (LCA) with power-law (exponential function) analysis (PLA), by applying segmented regression modeling to 1-year prescription claims data for three medications—alprazolam, opioids, and gabapentin—to predict abuse and/or diversion using power-law zone (PLZ) classification.

Results

In 1-year baseline observation, patients classified into the top PLZ groups (PLGs) were demographically and diagnostically similar to those in Lorenz-1 (top 1% of utilizers) and Lorenz-25 (top 25%). For prediction of follow-up (6-month post-baseline) Lorenz-1 use of alprazolam and opioids (i.e., potential abuse/diversion), PLA had somewhat lower sensitivity compared with LCA (83.5–95.4% vs. 99.5–99.9%, respectively) but better specificity (98.2–98.8% vs. 75.5%) and much better positive predictive value (PPV; 34.5–45.3% vs. 4.0–4.6%). Of top-PLG alprazolam- and opioid-treated patients, respectively, 20.7 and 9.9% developed incident (new) Lorenz-1 in followup, compared with < 3% of Lorenz-25 patients. For gabapentin, neither PLA nor LCA predicted incident Lorenz-1 (PPV = 0.0–1.4%). For all three medications, PLA sensitivity for follow-up hospitalization was < 5%, but specificity was better for PLA (97.3–99.2%) than for LCA (74.3–75.4%). PLA better identified patients at risk of future controlled substance abuse/diversion than did LCA, but the technique needs refinement before widespread use.

Keywords

  • Gabapentin
  • Alprazolam
  • Opioids
  • Abuse
  • Diversion
  • Power-law analysis
  • Lorenz-curve analysis

Introduction

For the United States (US) health care system, identifying and intervening on patients who are abusing or diverting controlled substances is a top priority because of high cost, morbidity, and mortality associated with fraud, waste, or abuse (FWA) [1, 2]. Numerous methods for identifying at-risk patients have been proposed [35]. Limiting their utility, most methods require integrated medical/pharmacy claims datasets, laboratory data, or complicated algorithms that may exceed the programming resources available in many health care organizations [35].

Various simpler analyses based solely on pharmacy claims data have been suggested [3, 6]. One common technique is Lorenz-curve analysis (LCA), which assesses the percentage of total medication supply dispensed to top utilizers, with Lorenz-1 indicating supply dispensed to the top 1% [68]. A Lorenz-1 of 15% or more indicates an abusable medication [8].

Although the Lorenz-1 metric is intuitively appealing and easily calculated, it indicates FWA that is already ongoing, perhaps at a dangerous level. One study of Lorenz-1 utilizers found dispensed dosages averaging 11,274 mg/day for gabapentin and 180 morphine-milligram equivalents (MME)/day for opioids [9], with both > 3 times the labeled/recommended dosage for any indication [10]. A follow-up study found that concomitant high-dosage consumption/diversion of gabapentin and opioids approximately doubled the risk of inpatient hospitalization (IPH) and quadrupled the risk of respiratory depression-related emergency or IPH care [11]. Thus, although important, Lorenz-1 may indicate damage that has already taken place. Ideally, health care systems would be able to predict medication FWA before it begins, acting on warning signs of future events.

One technique proposed to make predictions of this type, adapted from geophysical sciences, is power-law analysis (PLA), also known as fractal-scaling analysis [12], which was originally developed to predict catastrophic hurricanes, earthquakes, and other geophysical hazards [13]. In PLA, logarithmically transformed 2-dimensional plots of cumulative frequency against event magnitude are segmented into zones, each characterized by a linear equation (power law). “Transitions” (i.e., points at which the power law changes) indicate fundamental transformations in the nature of the events [12]. For example, a transition in the power law for hurricane wind speed magnitudes, identified by an early pioneer of the technique, indicated eyewall formation [12].

The present study was a proof-of-concept comparison of LCA with PLA, applied to prescription claims data for 3 medications: alprazolam, the benzodiazepine with the greatest abuse liability; [14, 15] opioids, which are a top public health concern because of an epidemic of misuse and overdose deaths; [1, 16] and gabapentin, a noncontrolled substance recently identified as a medication of abuse [10, 11].

Main text

Methods

Data source and sample

Study data were derived from the Truven Health Market Scan® Commercial Claims and Encounters Database for calendar years 2013–2015. The database, which comprises pharmacy claims, medical claims, and eligibility (enrollment) data for up to 50 million commercially insured enrollees annually, is commonly used in studies of US health care [17].

The study sample included enrollees aged 16–64 years with ≥ 2 claims for alprazolam, gabapentin, and/or any opioid during a 365-day period that began with the first observed pharmacy claim (baseline treatment year). To ensure accurate dosage calculations, patients using patches or fentanyl, or with missing or invalid dosages on any claims, were excluded. Patients using multiple study medications were not excluded; instead, each medication had its own baseline year, and concomitant uses of other study medications were measured.

Cohort group definitions

Based on utilization in the baseline treatment year, patients were categorized into groups using both PLA and LCA, including Lorenz-1 (top 1% of users) and Lorenz-25 (top 25%). These classifications were performed using SPSS v24.0 (IBM SPSS, Armonk, NY).

Specifically, for each patient and medication, total supply dispensed during the baseline year was summed as total mg for alprazolam and gabapentin and total MME for opioids, across all claims and strengths. For the LCA, again for each medication, patients were ranked according to total dispensed supply; and Lorenz-1 and quartile groups, including Lorenz-25, were identified.

The PLA also used rankings based on summed supply data, but patients were grouped differently: into 5-‰ bands from the 5th to 95th percentile, and into more granular (smaller) bands at the lowest and highest ends of the percentile distribution. Specifically, at the lowest end, patients were grouped as < 1st percentile and 1st  < 5th percentile. At the highest end, patients were grouped into single-percentage increments (e.g., 96th, 97th, etc.) to 99th, then into bands representing one-tenth of 1 percent increments (e.g., 99.1, 99.2%, etc.) up to the 99.9th percentile. This approach was taken because PLA predicts rare events, making a granular analysis of top utilizers necessary to determine the power law for each linear segment.

Summed data were then loaded into Excel (Microsoft, Redmond, WA). Power-law calculations, including identification of transition points and power-law zones (PLZs), were performed in Excel using a method similar to that of geophysical sciences for event magnitude and frequency [12, 13]. Specifically, for each utilization band, ranked from highest to lowest magnitude (i.e., dosage), medication supply/patient was calculated (summed supply ÷ summed patient count). Then, again for each band, patient frequencies (counts) were accumulated, whereas dosage magnitudes (supply/patient) were not accumulated. Both cumulative frequencies and magnitudes for each band were then log-transformed (log10; Additional file 1: Appendix S1). The resulting values were plotted, with the x-axis representing log10-magnitude, and the y-axis representing log10-cumulative frequency. Using a segmented-regression approach [18], PLZs were identified by visual inspection coupled with model fitting using linear regression.

Cohort group analyses

Two types of analyses were performed in SPSS, each including comparisons of groups based on LCA quartiles and on PLZs. The first assessed patient characteristics in the baseline treatment year. The second, a criterion validity assessment, was limited to subgroups of patients continuously enrolled through the 6 months after the baseline year (follow-up). Follow-up outcomes included Lorenz-1 utilization (i.e., potential FWA), IPH, and dosages/day standardized as Z-scores (distance from the mean measured in standard deviation units). Top-PLZ groups (PLGs) and top-LCA quartiles at baseline were defined as “at risk”; and rates of sensitivity, specificity, positive predictive value (PPV), and negative predictive value were calculated based on follow-up outcomes.

Results

For alprazolam, 4 separate power-law zones (linear segments) were identified, with R2 ranging from 0.990 to 0.999. For gabapentin and opioids, 3 zones were identified, with R2 = 0.961–0.998 (Additional file 1: Appendix S2, Additional file 1: Appendix S3).

Patient characteristics, baseline treatment year

For alprazolam and opioids, top PLGs were larger and used less medication compared with Lorenz-1 groups (Table 1; Additional file 1: Appendix S4). Threshold dosages for top-PLG and Lorenz-1, respectively, were 5.04 versus 7.40 mg/day alprazolam (i.e., 126 and 185% of maximum labeled/recommended dosage); and 130.2 versus 271.2 MME/day opioids (i.e., 260% vs. 542% of maximum labeled/recommended dosage). Of those in the top PLG, only 46.2% of alprazolam- and 36.9% of opioid-treated patients were Lorenz-1 in the baseline year. In all other respects, however, top PLG and Lorenz-1 patients were similar, demographically, diagnostically, and in proportions of claims exceeding recommended dosages. For example, comparing alprazolam-treated patients in PLG-4 and Lorenz-1, respectively, 63 and 64% were female; mean claims/month exceeding labeled/recommended dosage were 0.84 and 0.91; 21 and 20% were diagnosed with substance use disorder (SUD); and 59% in each group were diagnosed with anxiety. Similar patterns were observed in patients treated with opioids.
Table 1

Patient characteristics and utilization patterns by medication and group, baseline treatment year

 

PLG1

PLG2

PLG3

PLG4

Lorenz-25

Lorenz-1

Alprazolam (n)

283,970

187,266

57,854

11,662

137,047

5384

 % of sample

52.5

34.6

10.7

2.2

25.3

1.0

 Threshold dosage/daya

N/A

0.33

1.69

5.04

0.90

7.40

 Ratio threshold:maximum

N/A

0.08

0.42

1.26

0.23

1.85

 Female (%)

73.0

66.9

63.6

63.2

64.1

63.9

 Mean age

46

48

48

48

48

49

 Mean claims > max dose/monthb

0.13

0.22

0.33

0.84

0.33

0.91

 Lorenz-1 (%)

0.0

0.0

0.0

46.2

3.9

100.0

 Diagnoses and utilizationc %

      

  Anxiety

45.4

49.6

55.9

58.9

53.9

59.3

  Cancer

6.1

6.3

5.7

5.7

5.9

5.8

  Insomnia

12.2

14.5

14.4

15.5

14.6

15.3

  Pain

55.8

61.4

66.8

68.2

65.2

67.8

  SUD

8.1

12.9

18.5

20.6

16.9

19.6

 IPH (% with ≥ 1)

7.1

9.5

11.8

11.6

11.0

10.1

  Pain

2.2

3.3

4.5

4.6

4.1

4.1

  SUD

1.3

2.4

3.6

4.0

3.2

3.3

  Z drug hypnoticd

11.3

16.1

18.1

18.6

17.7

18.0

  Gabapentinc

3.7

6.6

8.9

8.9

8.2

8.5

  Opioidc

24.2

37.6

51.9

52.1

47.5

50.4

Gabapentin (n)

208,848

106,213

2476

N/A

81,534

3266

 % of sample

65.8

33.4

0.8

 

25.7

1.0

 Threshold dosage/daya

N/A

766.03

12,509.59

 

1034.25

10,356.16

 Ratio threshold:maximum

N/A

0.21

3.47

 

0.29

2.88

 Female (%)

64.6

61.7

59.1

 

61.2

60.1

 Mean age

50

51

52

 

51

52

 Mean claims > max dose/monthb

0.00

0.06

0.80

 

0.10

0.77

 Lorenz-1 (%)

0

0.7

100.0

 

4.0

100.0

 Diagnoses and utilizationc %

  Anxiety

20.6

22.7

27.9

 

23.0

27.3

  Cancer

8.1

8.5

8.6

 

8.5

8.4

  Insomnia

12.2

13.8

17.6

 

14.0

17.2

  Pain

84.4

86.4

90.0

 

86.7

89.7

  SUD

12.9

15.8

21.2

 

16.4

20.5

 IPH (% with ≥ 1)

14.1

16.2

17.1

 

16.4

16.7

  Pain

7.9

9.6

10.9

 

9.8

10.6

  SUD

2.9

3.4

5.0

 

3.5

4.7

 Benzodiazepined

21.3

26.6

27.8

 

26.9

27.2

 Z drug hypnoticd

9.7

12.9

12.9

 

13.0

12.7

 Opioidc

41.9

51.6

57.9

 

52.9

56.1

Opioids (n)

2,172,054

217,918

67,514

N/A

615,003

24,884

 % of sample

88.4

8.9

2.7

 

25.0

1.0

 Threshold dosage/daya

N/A

22.60

130.19

 

5.82

271.15

 Ratio threshold:maximum

N/A

0.45

2.60

 

0.12

5.42

 Female (%)

59.4

52.2

45.7

 

53.6

46.2

 Mean age

45

48

47

 

48

49

 Mean claims > max dose/monthb

0.08

0.52

1.44

 

0.44

1.63

 Lorenz-1 (%)

0

0

36.9

 

4.0

100.0

 Diagnoses and utilizationc %

  Anxiety

14.5

24.5

25.7

 

22.3

26.2

  Cancer

6.6

7.1

6.3

 

7.4

6.6

  Insomnia

7.8

12.5

12.7

 

11.9

13.6

  Pain

66.8

87.8

83.1

 

85.1

88.3

  SUD

9.5

24.8

36.4

 

20.8

32.2

 IPH (% with ≥ 1)

12.5

17.9

15.5

 

18.7

15.6

  Pain

4.9

10.4

9.2

 

11.3

9.8

  SUD

1.5

4.5

5.1

 

3.8

5.0

 Benzodiazepined

14.2

35.4

38.2

 

30.8

41.2

 Z drug hypnoticd

6.4

14.8

14.4

 

13.2

15.2

 Gabapentinc

4.9

16.9

16.5

 

14.1

17.0

IPH inpatient hospital stay, Lorenz-1 top 1% of utilizers, Lorenz-25 top quartile (25%) of utilizers, mg milligrams, MME morphine-milligram equivalents, PLG power-law group, SUD substance use disorder

aMedication supply was measured as milligrams for alprazolam (n = 540,752) and gabapentin (n = 317,537), and MMEs for opioids (n = 2,457,486). All medication claims were measured in the baseline treatment year (i.e., 12-month period beginning with the first observed medication claim of the type shown in the row label); sample is not limited to new utilizers. Threshold is the dosage that defines the category lower limit; for example, > 0.33 and ≤ 1.69 mg defined PLZ-2 alprazolam

bTotal supply dispensed in each claim divided by days supply; rate was measured as total number of claims exceeding labeled/recommended dosage (4 mg/day alprazolam, 3600 mg/day gabapentin; 50 MME/day opioids), divided by 12

cMeasured in the baseline treatment year. Diagnosis codes are shown in Additional file 1: Appendix S4

dBenzodiazepines measured: clonazepam, diazepam, lorazepam and, for users of gabapentin and opioids, alprazolam. Z-drugs measured: eszopiclone and zolpidem. Percentages of patients with ≥ 2 claims

In contrast, for those treated with gabapentin, the threshold dosage for the top PLG was higher than the Lorenz-1 threshold, at 12,510 and 10,356 mg/day, respectively; and 100% of PLG-3 patients were Lorenz-1 (Table 1). However, gabapentin PLG-3 and Lorenz-1 patients were similar in other respects.

For all 3 medications, Lorenz-25 patient groups were characterized by relatively low dosage thresholds (ranging from 12 to 29% of maximum; Table 1). Baseline SUD prevalence rates were generally lower for these groups than for the top PLGs and Lorenz-1 groups, but otherwise, the groups were demographically and diagnostically similar.

Criterion validity analyses

From the 1-year baseline to 6-month follow-up periods for all 3 medications, mean daily dosages changed only modestly for most treated patients in PLG-1 and PLG-2 (Fig. 1). In contrast, for those in each top PLG, a distinctive splitting pattern occurred, in which a proportion of patients experienced substantial increases in dispensed dosage from baseline to follow-up. The LCA was dominated by Lorenz-25, with no visible distinctions among quartiles to characterize the threshold dosage at which the splitting pattern began (Additional file 1: Appendix S5).
Fig. 1
Fig. 1

Criterion validity analyses: standardized mean dosage/day, baseline treatment and 6-month follow-up, by PLGs. PLG power-law group

For prediction of follow-up Lorenz-1 use of alprazolam and opioids, PLA had somewhat lower sensitivity compared with LCA (83.5–95.4% vs. 99.5–99.9%, respectively) but better specificity (98.2–98.8% vs. 75.5%) and much better PPV (34.5–45.3% vs. 4.0–4.6%; Table 2). Of those in the top PLG for alprazolam and opioids, respectively, 20.7 and 9.9% went from utilization < Lorenz-1 at baseline to Lorenz-1 in follow-up (i.e., incident Lorenz-1). For the same respective medications, only 2.5 and 1.3% in Lorenz-25 went on to incident Lorenz-1. For patients treated with gabapentin, PPV for incident Lorenz-1 was < 2% for both techniques.
Table 2

Criterion validity assessment: Lorenz-1 status and inpatient hospital use

Power law zone

Alprazolam (n = 463,203)

Gabapentin (n = 267,693)

Opioid (n = 2,077,393)

 

PLG1

PLG2

PLG3

PLG4

PLG1

PLG2

PLG3

 

PLG1

PLG2

PLG3

 

N of cases

241,992

161,677

49,603

9931

174,989

90,590

2114

 

1,833,724

186,258

57,411

 

Lorenz-1 in follow-up

0.0

0.0

1.6

45.3

0.0

1.4

58.5

 

0.0

0.5

34.5

 

Lorenz-1 sensitivity, specificity, PPV, NPVa (%)

83.5, 98.8, 45.3, 99.8

48.9, 99.7, 58.5, 99.5

95.4, 98.2, 34.5, 100.0

 Incident Lorenz-1 in follow-up

0.0

0.0

1.6

20.7

0.0

1.1

0.0

 

0.0

0.5

9.9

 

Incident Lorenz-1 sensitivity, specificity, PPV, NPVa (%)

69.9, 98.3, 20.7, 99.8

0.0, 99.2, 0.0, 99.6

85.5, 97.5, 9.9, 100.0

 IPH observation year

3.5

5.0

6.6

6.3

7.0

8.7

9.5

 

5.7

9.3

8.4

 

 IPH follow-up

3.6

5.0

6.6

7.3

6.7

8.4

9.4

 

4.5

8.1

8.2

 

 IPH % change

2.9

0.0

0.0

15.9

− 4.3

− 3.4

− 1.1

 

− 21.1

− 12.9

− 2.4

 

IPH sensitivity, specificity, PPV, NPV (%)

3.5, 97.9, 7.3, 95.6

1.0, 99.2, 9.4, 92.7

4.6, 97.3, 8.2, 95.2

 SUDb IPH observation year

0.6

1.2

2.0

2.0

1.4

1.7

2.6

 

0.7

2.3

2.6

 

 SUDb IPH follow-up

0.6

1.2

2.2

2.8

1.3

1.6

2.5

 

0.7

2.2

2.9

 

 SUDb IPH % change

0.0

0.0

10.0

40.0

− 7.1

− 5.9

− 3.8

 

0.0

− 4.3

11.5

 

SUD IPH sensitivity, specificity, PPV, NPVa (%)

5.7, 97.9, 2.8, 99.0

1.4, 99.2, 2.5, 98.6

9.4, 97.3, 2.9, 99.2

Utilization quartile

Q1

Q2

Q3

Q4

Q1

Q2

Q3

Q4

Q1

Q2

Q3

Q4

N of cases

133,446

108,543

103,532

117,680

71,889

60,802

65,223

69,779

486,760

537,304

528,704

524,625

Lorenz-1 in follow-up

0.0

0.0

0.0

4.6

0.0

0.0

0.0

3.6

0.0

0.0

0.0

4.0

Lorenz-1 sensitivity, specificity, PPV, NPVa (%)

99.5, 75.5, 4.6, 100.0

99.6, 74.6, 3.6, 100.0

99.9, 75.5, 4.0, 100.0

 Incident Lorenz-1 in follow-up

0.0

0.0

0.0

2.5

0.0

0.0

0.0

1.4

0.0

0.0

0.0

1.3

Incident Lorenz-1 sensitivity, specificity, PPV, NPVa (%)

99.2, 75.1, 2.5, 100.0

99.1, 74.2, 1.4, 100.0

99.7, 75.0, 1.3, 100.0

 IPH observation year

3.2

4.0

4.7

6.0

6.4

7.1

8.2

8.9

2.8

4.7

7.3

9.3

 IPH follow-up

3.4

3.9

4.7

6.1

6.1

6.9

7.7

8.5

3.2

3.8

5.2

7.4

 IPH % change

6.2

− 2.5

0.0

1.7

− 4.7

− 2.8

− 6.1

− 4.5

14.3

− 19.1

− 28.8

− 20.4

IPH sensitivity, specificity, PPV, NPVa (%)

34.6, 75.0, 6.1, 96.1

30.5, 74.3, 8.5, 93.1

38.0, 75.4, 7.4, 95.9

 SUDb IPH observation year

0.5

0.8

1.1

1.7

1.2

1.4

1.5

1.7

0.3

0.5

0.8

1.8

 SUDb IPH follow-up

0.5

0.8

1.1

1.9

1.2

1.3

1.4

1.7

0.4

0.5

0.7

1.8

 SUDb IPH % change

0.0

0.0

0.0

11.8

0.0

− 7.1

− 6.7

0.0

33.3

0.0

− 12.5

0.0

SUD IPH sensitivity, specificity, PPV, NPVa (%)

45.9, 74.8, 1.9, 99.2

31.6, 74.0, 1.7, 98.7

52.4, 75.0, 1.8, 99.4

Earliest baseline year from January 1, 2013, through December 31, 2013, with follow-up from January 1, 2014, through June 30, 2014. Latest baseline year from July 1, 2014, through June 30, 2015, with follow-up from July 1, 2015, through December 31, 2015

IPH inpatient hospital, NPV negative predictive value, PLG power-law group, PPV positive predictive value, Q quartile, SUD substance use disorder

aAssuming that top PLG category and fourth quartile are predicted as at risk

bDiagnosis codes in Additional file 1: Appendix S4

For follow-up IPH, sensitivity was much less for PLA (1.0–4.6%) than for LCA (30.5–38.0%). However, both specificity and PPV were improved using PLA.

Discussion

This proof-of-concept study applied PLA, which was originally developed to predict catastrophic events in physical systems, for the new purpose of predicting FWA development based solely on pharmacy claims data. For controlled substances, PLA performed better than did LCA at identifying a cohort of patients not currently engaging in, but at risk of developing, future FWA, with somewhat reduced sensitivity but better specificity and PPV. Notably, patients in the top PLGs, Lorenz-25, and Lorenz-1 were demographically and clinically similar at baseline in all respects other than pharmacy utilization. For a health care organization attempting to target FWA mitigation efforts to enrollees most in need of them, the improved PPV and specificity outcomes achieved with PLA are potentially important. However, in this preliminary analytic stage, PLA’s case-finding ability, especially for IPH, was not sufficient for widespread application. Several areas for future development are indicated.

Foremost, results suggest that patients in top PLGs may be at increased risk of future abuse/diversion; yet, top-PLG status is clearly not a perfect predictor of FWA. Future analyses should assess FWA predictors in subsamples limited to top-PLG patients. Bollinger-band analysis, which has been used to predict surges in use of intensive-care services [19], might provide additional insights into medication demand changes in top PLGs. Perhaps the lower PPVs for IPH compared with Lorenz-1 indicate detection of diversion, rather than consumption, of medication.

Additionally, the most common use of PLA in the physical sciences is performed at the regional level, predicting federal expenditures on catastrophic events for specific geographic areas [12]. The increasing availability of data from prescription drug monitoring programs (PDMP) [20] may represent an opportunity to apply PLA to regional utilization and mortality data, thereby providing health care payers with better information about which regions are most at risk, and which PDMP features may most effectively mitigate FWA-related harms.

Conclusion

Application of PLA to pharmacy claims data is a promising new method for identifying patients at risk of FWA but needs additional refinement prior to widespread use. Potential future applications may include proactive management of known or emerging medications of abuse [21].

Limitations

If PLA predicts fundamental system change, it is not clear why only a portion of patients in each top PLG went on to experience large dosage increases, indicating potential FWA. Our application of PLA to all treated patients with ≥ 2 claims may have been overly broad—perhaps analogous to measuring a catastrophic event of any type, rather than the technique’s original purpose of measuring only one type of catastrophic event. Future applications might limit samples to more restricted subgroups and outcomes specific to key clinical situations; for example, development of FWA in patients with SUD, or of SUD in patients treated with opioids for chronic noncancer pain [22]. Similarly, since recent work has suggested that gabapentin misuse is likely only in patients who either have a SUD diagnosis or are concomitantly using opioids [23], a future sample might be limited to patients with concomitant gabapentin/opioid use to improve PLA’s PPV for gabapentin misuse. Moreover, the 6-month follow-up period, the maximum possible for this dataset and design, was not long enough to measure long-term developments. Additional analyses following patients for longer time periods may yield more information about FWA development.

Abbreviations

US: 

United States

FWA: 

fraud, waste, or abuse

LCA: 

Lorenz-curve analysis

mg: 

milligrams

MME: 

morphine-milligram equivalents

IPH: 

inpatient hospitalization

PLA: 

power-law analysis

PLZ: 

power-law zones

PLG: 

power-law groups

PPV: 

positive predictive value

SUD: 

substance use disorder

PDMP: 

prescription drug monitoring program

CF: 

cumulative frequency

Q: 

quartile

CPT: 

current procedural terminology

HCPCS: 

Healthcare Common Procedure Coding System

ICD: 

International Classification of Diseases

Declarations

Authors’ contributions

KAF and MLR performed concept and design, assisted by AMP, JHR, and DAS. KAF, MLR, and JHR performed data analyses and constructed the data presentations. MLR was the primary methodological expert, and AMP was the primary clinical expert, in data interpretation. KAF drafted the manuscript, assisted by AMP. All authors reviewed the manuscript and contributed to intellectual content. All authors read and approved the final manuscript.

Acknowledgements

Not applicable.

Competing interests

AMP, DAS, KAF and JHR declare that they have no competing interests. MLR is a consulting engineer whose services include the development and application of the techniques discussed in this article. KAF and JHR are MLR’s spouse and son, respectively.

Availability of data and materials

The data that support the findings of this study are available from Truven Health Market Scan® Commercial Claims and Encounters Database but restrictions apply to the availability of these data, which were used under license for the current study, and so are not publicly available. Aggregated data that were used to define the power-law zones are available from the authors upon reasonable request.

Consent to publish

Not applicable.

Ethics approval and consent to participate

The Institutional Review Board (IRB) Committee of Midwestern University (Glendale, Arizona) found that this study fulfilled criteria for IRB Exemption per Code of Federal Regulations, Title 45, Part 46, section 101 (45 CFR 26.101).

Funding

This study was not funded.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Authors’ Affiliations

(1)
College of Pharmacy-Glendale, Midwestern University, 19555 N 59th Ave, Glendale, AZ 85308, USA
(2)
Northeastern University School of Pharmacy and Massachusetts General Hospital, Boston, USA
(3)
Wood Environment & Infrastructure Solutions, Phoenix, USA
(4)
Kathleen Fairman LTD, Phoenix, USA

References

  1. Rudd RA, Seth P, David F, Scholl L. Increases in drug and opioid-involved overdose deaths—United States, 2010–2015. MMWR Morb Mortal Wkly Rep. 2016;65(5051):1445–52.View ArticlePubMedGoogle Scholar
  2. Oderda GM, Lake J, Rudell K, Roland CL, Masters ET. Economic burden of prescription opioid misuse and abuse: a systematic review. J Pain Palliat Care Pharmacother. 2015;29(4):388–400.View ArticlePubMedGoogle Scholar
  3. Canan C, Polinski JM, Alexander GC, Kowal MK, Brennan TA, Shrank WH. Automatable algorithms to identify nonmedical opioid use using electronic data: a systematic review. J Am Med Inform Assoc. 2017;24(6):1204–10.View ArticlePubMedGoogle Scholar
  4. Starner CI, Qiu Y, Karaca-Mandic P. Gleason PP. J Manag Care Spec Pharm. 2016;22(12):1403–10.View ArticlePubMedGoogle Scholar
  5. Cochran G, Woo B, Lo-Ciganic WH, Gordon AJ, Donohue JM, Gellad WF. Defining non-medical use of prescription opioids within health care claims: a systematic review. Subst Abus. 2015;36(2):192–202.View ArticlePubMedPubMed CentralGoogle Scholar
  6. Birt J, Johnston J, Nelson D. Exploration of claims-based utilization measures for detecting potential nonmedical use of prescription drugs. J Manag Care Pharm. 2014;20(6):639–46.Google Scholar
  7. Hallas J. Drug utilization statistics for individual-level pharmacy dispensing data. Pharmacoepidemiol Drug Saf. 2005;14:455–61.View ArticlePubMedGoogle Scholar
  8. Gjerden P, Bramness JG, Slordal L. The use and potential abuse of anticholinergic antiparkinson drugs in Norway: a pharmacoepidemiological study. Br J Clin Pharmacol. 2009;67(2):228–33.View ArticlePubMedGoogle Scholar
  9. US Centers for Disease Control and Prevention. Calculating total daily dose of opioids for safer dosage. https://www.cdc.gov/drugoverdose/pdf/calculating_total_daily_dose-a.pdf. Accessed 05 Jun 2018.
  10. Peckham AM, Fairman KA, Sclar DA. Prevalence of gabapentin abuse: comparison with agents with known abuse potential in a commercially insured US population. Clin Drug Invest. 2017;37(8):763–73.View ArticleGoogle Scholar
  11. Peckham AM, Fairman KA, Sclar DA. All-cause and drug-related medical events associated with overuse of gabapentin and/or opioid medications: a retrospective cohort analysis of a commercially insured US population. Drug Saf. 2018;41(2):213–28.View ArticlePubMedGoogle Scholar
  12. United States Geological Survey. Natural disasters-forecasting economic and life losses. USGS fact sheet. https://pubs.usgs.gov/fs/natural-disasters/. Accessed 05 Jun 2018.
  13. Fairman KA, Rucker ML. Fractal mathematics in managed care? How a simple and revealing analysis could improve the forecasting and management of medical costs and events. J Manag Care Pharm. 2009;15(4):351–8.PubMedGoogle Scholar
  14. Shukla L, Bokka S, Shukla T, et al. Benzodiazepine and “Z-drug” dependence: data from a tertiary care center. Prim Care Companion CNS Disord. 2017. https://doi.org/10.4088/PCC.16br02025.PubMedView ArticleGoogle Scholar
  15. Substance Abuse and Mental Health Services Administration. Emergency department visits involving nonmedical use of the anti-anxiety medication alprazolam. 2014. https://archive.samhsa.gov/data/2k14/DAWN153/sr153-alprazolam-2014.pdf. Accessed 05 Jun 2018.
  16. Kanouse AB, Compton P. The epidemic of prescription opioid abuse, the subsequent rising prevalence of heroin use, and the federal response. J Palliat Care Pharmacother. 2015;29(2):102–14.View ArticleGoogle Scholar
  17. Truven Health Analytics. MarketScan bibliography. http://truvenhealth.com/markets/life-sciences/products/data-tools/marketscan-bibliography. Accessed 05 Jun 2018.
  18. Vieth E. Fitting piecewise linear regression functions to biological responses. J Appl Physiol. 1989;67(1):390–6.View ArticlePubMedGoogle Scholar
  19. Pagel C, Ramnarayan P, Ray S, Peters MJ. A novel method to identify the start and end of the winter surge in demand for pediatric intensive care in real time. Pediatr Crit Care Med. 2015;16(9):821–7.View ArticlePubMedGoogle Scholar
  20. Moyo P, Simoni-Wastila L, Griffin BA, Onukwugha E, Harrington D, Alexander GC, Palumbo F. Impact of prescription drug monitoring programs (PDMPs) on opioid utilization among Medicare beneficiaries in 10 US states. Addiction. 2017;112(10):1784–96.View ArticlePubMedGoogle Scholar
  21. Peckham AM, Fairman KA, Sclar DA. Policies to mitigate nonmedical use of prescription medications: how should emerging evidence of gabapentin misuse be addressed? Exp Opin Drug Saf. 2018;17(5):519–23.View ArticleGoogle Scholar
  22. Dowell D, Haegerich T, Chou R. CDC guideline for prescribing opioids for chronic pain—United States, 2016. JAMA. 2016;315(15):1624–45.View ArticlePubMedGoogle Scholar
  23. Peckham AM, Evoy KE, Covvey JR, Ochs L, Fairman KA, Sclar DA. Predictors of gabapentin overuse with or without concomitant opioids in a commercially insured US population. Pharmacotherapy. 2018;38(44):436–43.View ArticlePubMedGoogle Scholar

Copyright

© The Author(s) 2018

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