# Assessing the Impact of Patient Characteristics on Genetic Clinical Pathways: A Regression Approach
## 3 Results
### Analysis of Variability between and within Pathways  
Descriptive Statistics  
Among the variables in the database that could affect the pathways, the length of the clinical pathway is considered a proxy for the complexity of care and the costliness of the clinical pathway; the variables chosen as possible regressors are maternal age, week of pregnancy (at the time of first admission to the facility), live births (from previous pregnancies), miscarriages (from previous pregnancies), voluntary pregnancy interruptions (VPI), and the referring medical doctor. These variables constitute the regressors of the statistical estimates performed in the models. The reference sample contains 2119 observations. However, a significant proportion of observations (1266) are attributable to a particular type of pathway, of very short length (defined as \"day-hospital\") and with peculiar characteristics, which refers to the entry motivation \"maternal age\". This sub-sample (which we can define \"Maternal Age-EMA\") is rather homogeneous even though it includes two entry motivations (amniocentesis and chorionic villi for women over 35 years old). It appears, on the other hand, rather interesting to carry out a descriptive analysis for the other sub-sample, i.e., the one consisting of motivations other than just maternal age, which will henceforth be referred to as 'Not-EMA' for brevity. Another sub-sample that appears to be interesting to examine is that of foreign mothers. These present significantly different characteristics, in terms of age and weeks of pregnancy. For each regressor, the statistics presented in Table 12 refer both to the total sample and the not-EMA and foreign women sub-samples. The mothers in the whole sample presented themselves on average at the twelfth week of pregnancy. This result is not accidental, as the first useful information about the fetus is generally available after the third month of pregnancy. However, in the two subsamples considered, mothers arrived later in their gestation. Testing the hypothesis that the mean in the not-EMA sub-sample is equal to the mean of the whole sample, we obtain a result (4.70) that allows us to reject the hypothesis that the two averages are equal at the 5% level of significance. The same test, on the subsample of foreign mothers, provides a result equal to 6.71. With respect to the average age in the total sample, an average value of 35.5 years is recorded. This result is influenced by the fact that the sample contains mothers who have undergone compulsory examinations due to maternal age. The probability distribution is consequently strongly influenced by this self-selection. This is confirmed by the fact that the average age for the not-EMA sub-sample is lower (32.5 years). A hypothesis test that the mean is 35.45 against the alternative that it is less than 35.45 provides a result equal to \(-\)15.43. The hypothesis that the two averages are equal can be strongly rejected. Foreign mothers were significantly younger. The hypothesis test on the subsample of \begin{table}
\begin{tabular}{l c c c c c} \hline \hline  & **Mean** & **Median** & **St. Dev.** & **Min** & **Max** \\ \hline Sample size = 2119 & & & & & \\ Weeks of pregnancy & 11.97 & 12 & 4.01 & 4 & 40 \\ Age & 35.45 & 36 & 4.92 & 15 & 48 \\ Sample size = 853—Not-EMA & & & & & \\ Weeks of pregnancy & 12.85 & 12 & 5.46 & 4 & 37 \\ Age & 32.38 & 33 & 5.81 & 16 & 48 \\ Sample size = 321—Foreign women & & & & & \\ Weeks of pregnancy & 13.99 & 13 & 5.35 & 4 & 40 \\ Age & 32.56 & 34 & 6.27 & 15 & 46 \\ \hline \hline \end{tabular}
\end{table} 
Table 12: Descriptive statistics for week of pregnancy and maternal age. foreign mothers provided a result equal to \(-8.25\). Again, the hypothesis that the mean is equal is strongly rejected. Figure 4 contains the estimated density functions for the variable weeks of pregnancy, for the whole sample (a), and for the two subsamples considered: not-EMA (b) and foreign women (c).