laktat_sepsis_vergleich.png

# ===========================================================================
# MODULE 10 · Lactate: Sepsis vs. Nicht-Sepsis
# ===========================================================================
print("[10] Laktat Sepsis-Vergleich ...")

df_sep = df.dropna(subset=["laktat_mmol_l"]).copy()
sepsis_vals    = df_sep.loc[df_sep["sepsis_gruppe"] == "Sepsis",      "laktat_mmol_l"]
non_sepsis_vals = df_sep.loc[df_sep["sepsis_gruppe"] == "Nicht-Sepsis", "laktat_mmol_l"]

# Statistics
_, p_val   = stats.mannwhitneyu(sepsis_vals, non_sepsis_vals, alternative="two-sided")
n1, n2 = len(sepsis_vals), len(non_sepsis_vals)
u_stat, _ = stats.mannwhitneyu(sepsis_vals, non_sepsis_vals, alternative="two-sided")
# Rank-biserial r as effect size
r_effect = 2 * u_stat / (n1 * n2) - 1

fig, ax = plt.subplots(figsize=(6, 5))

palette_sep = {"Sepsis": EVENT, "Nicht-Sepsis": PRIMARY}
order = ["Nicht-Sepsis", "Sepsis"]

sns.boxplot(
    data=df_sep, x="sepsis_gruppe", y="laktat_mmol_l",
    hue="sepsis_gruppe", order=order, palette=palette_sep,
    width=0.45, linewidth=0.9, fliersize=2.5,
    flierprops=dict(marker="o", alpha=0.35),
    legend=False, ax=ax,
)
sns.stripplot(
    data=df_sep, x="sepsis_gruppe", y="laktat_mmol_l",
    hue="sepsis_gruppe", order=order, palette=palette_sep,
    size=3, alpha=0.35, jitter=True, legend=False, ax=ax,
)

ax.set_xlabel("")
ax.set_ylabel("Laktat (mmol/l)")
ax.set_title("Laktat bei Sepsis vs. Nicht-Sepsis")

# Sample size as a second line in each category label (no overlap)
ax.set_xticks(range(len(order)))
ax.set_xticklabels([f"{g}\nn = {df_sep[df_sep['sepsis_gruppe'] == g].shape[0]}"
                    for g in order])

# Significance annotation
y_max = df_sep["laktat_mmol_l"].quantile(0.97)
p_txt = f"p = {p_val:.4f}" if p_val >= 0.0001 else "p < 0.0001"
ax.annotate(
    "", xy=(1, y_max * 0.96), xytext=(0, y_max * 0.96),
    arrowprops=dict(arrowstyle="-", color="#666666", lw=1.0),
)
ax.text(0.5, y_max * 0.98,
        f"Mann-Whitney-U\n{p_txt}\nEffektgröße r = {r_effect:.2f}",
        ha="center", va="bottom", fontsize=9, color="#333333")

fig.subplots_adjust(bottom=0.12)
save(fig, ASSETS / "10-inferenzstatistik" / "assets" / "laktat_sepsis_vergleich.png")