1.6 Summary Tables in Studies of Medical Product Utilization

In studies of medical product utilization, the QRP Reporting Tool outputs many summary tables that provide more details on various measures of interest. There are seven measures of medical product utilization that the QRP Reporting Tool can summarize: 1) days supply in each dispensing of the treatment episode, 2) cumulative treatment duration, 3) duration of each treatment episode, 4) duration of gaps between treatment episodes, 5) current filled daily dose in each dispensing of the treatment episode, 6) average filled daily dose in each treatment episode, and 7) cumulative filled dose. Each of these measures can be summarized in a table containing all specified cohort groups.

1.6.1 Output

For each utilization measure, there is a base unit upon which computation of the measure relies. For the purposes of this documentation, we refer to this unit as the “counting variable”, since each measure is summarized according to this variable. Because days supply and current filled daily dose are calculated on the basis of dispensings, the counting variable for these utilization measures is the dispensing. Conversely, cumulative treatment duration and cumulative filled dose are calculated on the basis of the patient, so here the counting variable is patient. Finally, treatment episode duration, treatment episode gap duration, and average filled daily dose use episodes as the counting variable.

Users will note that each of these measures are continuous measures that can be summarized using descriptive statistics including minimum, maximum, mean, standard deviation, median, and percentiles. In addition to summary tables including these descriptive statistics, users also have the option to specify categorical groupings of the continuous measures and output the number of dispensings, patients, or episodes in each category (as relevant). To protect patient privacy and maintain return of the minimum necessary amount of information, median and percentiles are not reported for dose measures.

Each unique measure-counting variable restriction that is summarized in the report will receive its own Table Number, appearing in the order shown below in Table 1.10. When users choose to output summaries both categorically and continuously, the former will have a suffix Table Letter “a,” and the latter “b.” Any user-specified stratifications will follow this pattern with the Letter “c” for the categorical summary and “d” for the continuous summary of the given measure, then “e” and “f” for the next requested stratification for that measure, and so on. Tables are titled as shown in the Table 1.10 below.

Because categorizations of dose measures are performed at the cohort group level, a superscript appears next to each cohort group label, with the corresponding footnote reading: “[Group Label]: [Dose Category 1 Label] = W-X [UNIT]; [Dose Category 2 Label] = Y-Z [UNIT]; …” and so on for the number of categories.

If race categories with ten or fewer counts of patients are collapsed into the “Unknown” category, the following footnote is output: “Includes members classified as having an unknown race by the Data Partner and patients in race categories where the total member count is between one and ten.”

Table 1.10: Requestable Summary Tables in Studies of Medical Product Utilization
Utilization Measure	Counting Variable¹	Counting Variable Restriction	Table Order	Table Letter	Table Title, followed by ‘for [ReportTitle]² in the [Database Name]³ from [Query Start]⁴ to [Query End]⁵’
Days Supply	Dispensings^a	N/A	1	a	Categorical Summary of Days Supply per Dispensing
Days Supply	Dispensings^a	N/A	1	b	Continuous Summary of Days Supply per Dispensing
Duration of Cumulative Exposure	Patients	N/A	2	a	Categorical Summary of Patients’ Cumulative Treatment Episode Durations
Duration of Cumulative Exposure	Patients	N/A	2	b	Continuous Summary of Patients’ Cumulative Treatment Episode Durations
Duration of Treatment Episodes	Treatment Episodes	N/A	3	a	Categorical Summary of All Treatment Episodes
	Treatment Episodes	N/A	3	b	Continuous Summary of All Treatment Episodes
	Treatment Episodes	1st	4	a	Categorical Summary of First Treatment Episodes
	Treatment Episodes	1st	4	b	Continuous Summary of First Treatment Episodes
	Treatment Episodes	≥2nd	5	a	Categorical Summary of Second and Subsequent Treatment Episodes
	Treatment Episodes	≥2nd	5	b	Continuous Summary of Second and Subsequent Treatment Episodes
Duration of Gaps between Treatment Episodes	Treatment Episodes	N/A	6	N/A	Continuous Summary of All Treatment Episode Gaps
	Treatment Episodes	1st	7	N/A	Continuous Summary of First Treatment Episode Gaps
	Treatment Episodes	≥2nd	8	N/A	Continuous Summary of Second and Subsequent Treatment Episode Gaps
Current Filled Daily Dose	Dispensings^a	N/A	9	N/A	Summary of Filled Daily Dose in Each Dispensing
Average Filled Daily Dose	Treatment Episodes	N/A	10	N/A	Summary of Average Filled Daily Dose in Each Treatment Episode
Average Filled Daily Dose	Treatment Episodes	1st	11	N/A	Summary of Average Filled Daily Dose in Each Patient’s First Valid Episode
Cumulative Filled Dose	Patients	N/A	12	N/A	Summary of Cumulative Filled Dose in All Treatment Episodes
Cumulative Filled Dose	Patients	1st	13	N/A	Summary of Cumulative Filled Dose in Each Patient’s First Treatment Episode
^a The number of dispensings after adjusting for same-day dispensings, as described in the QRP documentation.
¹ The label "Number of Patients" is printed on all tables that represent 1 episode per patient (including tables where counting variable is "treatment episodes").
² [Report Title] is user-specified in the QRP Report Label File.
³ [Database Name] is user-specified in QRP Report DP Info File.
⁴ [Query Start] is user-specified in `qrp.MonitoringFile`.
⁵ [Query End] is the maximum date of all the included data partner end dates (unless an explicit follow-up end date is specified in <code>qrp.MonitoringFile</code> and is earlier than the maximum data partner end date, in which case the end date is the follow-up end date).

1.6.2 User Options

If desired, users can choose to output multiple cohort groups under a combined header by specifying the appropriate parameter in the QRP Report Label File.

In order to output categories of the continuous utilization measure in summary tables, users must pre-specify integer-based divisions that should cover the full spectrum of possible values using the QRP Report Table File. In each division, the upper bound is binding and the final division should end with the “+” symbol. In other words, the count variable will fall within a given division when the value of the measure is less than or equal to the upper bound of that division.

The exception to specifying categories of utilization measures is when summarizing dose. In this case, categories are pre-defined in the QRP using qrp.Type5File and carried over into the report. Custom labels for categories of each dose measure can be specified using the QRP Report Label File. When no labels are specified, dose measure categories are labeled “Dose Group 1,” “Dose Group 2,” and so on.

In addition to summarizing all instances of the relevant counting variable, certain summary tables in medical product utilization studies can also be restricted to describing the 1) first occurrence of the counting variable, and 2) the second and subsequent occurrence of the counting variable. Measures that can be restricted in this way are shown in this section’s Table 1.

Unlike summary tables in other study designs, in order to request stratified summary table for a study of medical product utilization, users must also request the “overall” stratification in the QRP Report Table File. All stratifications for a given measure are described using the same categorizations. Users can request stratifications on the following factors: data partner, sex, age group, race, Hispanic ethnicity, sex by age group, sex by race, sex by Hispanic ethnicity, age group by race, and age group by Hispanic ethnicity.

1.6.3 Calculations

Before each of the seven continuous measures are presented in the QRP Report, they must first be aggregated. To do so, the QRP Reporting Tool identifies unique values of each measure and sums the relevant counting variable from each data partner for each unique combination of QRP run, cohort group, stratification level, and restriction.

Definition 1.1 (Type 5 Calculations) Given:

\(x_i\) is the non-missing value of the untilization measure for observation \(i\);
\(f_i\) is the frequency that is associated with \(x_i\);
\(n\) is the number of non-missing values of \(x_i,\sum f_i\);
\(n_c\) is the number of non-missing values of \(x_i,\sum f_i\) contained within a given category;
\(p\) is the \(\frac{t}{100}\) for the \(t^{th}\) percentile;
\(j\) is the integer component of np where \(np\ =\ j+\ g\);
\(g\) is the fractional component of np where \(np\ =\ j+\ g\);

Then, each metric reported in summary tables of medical product utilization studies is calculated as described in Table 1.11 below.

Table 1.11: Calulations for each metric reported in summary tables of medical product utilization
Metric Reported	Calculation
Total Number of [count variable]	\(n\)
Number of [count variable] in category	\(n_c\)
Percent of all [count variable]	\(n_c/n\times100\)
Minimum	The minimum value of \(x_i\)
Q1, Median, Q3	\(y=\frac{1}{2}\left(x_j+x_{j+1}\right)\) if \(g=0\); \(y=x_{j+1}\) if \(g\gt0\)
Maximum	The maximum value of \(x_i\)